"Oi! Wot're you doing?" yelled Jack.

Three cubs loitering outside the parish hall were of no interest to the men with the camera, who decided to ignore them. Neither seemed very cheerful. The taller, dark-haired one appeared faintly guilty; the smaller's cherubic blondness was belied by an expression of profound irritation.

The irritation was even less disguised when he spoke, rubbing his gloved hands together. "Hurry up, Alec. How many more are there?"

"How was I to know that film wouldn't develop properly? If we don't have this on Himmler's desk by first thing Monday, we'll both be for the high jump." The tall one checked a notebook. "Four. Tiling, cracks in the brickwork, possible subsidence and something illegible you wrote."

"There's the tiling problem," the small one pointed out to his colleague, who quickly photographed it. "Let's get this done quickly. I need to get home."

"Francine not impressed?"

His colleague did not reply directly as they walked around the corner. "Let's just say there are other things I should be doing on Saturday morning."

"I bet they're the blokes who're pulling down the 'all!" said Jack, loudly offering them a line of his grandmother's, "Tearing the 'eart outta the community, they are!"

Timothy, watching them depart, was as sceptical as he often was at Jack's proclamations. Whoever they were he sympathised; his own morning had been bad enough, even without a Francine, about whom he made his own deductions. Their rehearsal had started well enough. When not on stage he had enjoyed watching Jack, Peter and Gary, and shortly after ten Nurse Miller arrived to run through a new piece which Bagheera wanted him to play, accompanied by Akela, who wanted to start costuming the principals. This was when things started to go wrong. The piece in question was the Sailor's Hornpipe and he had been mischievously excited by the prospect of tormenting his peers with its gradual acceleration. On his father's record of the Last Night of the Proms, it sounded incredibly straightforward. In reality, it was exceptionally difficult. Even sight-reading at the speed of arthritic tortoise, he could barely make the leaps and although Nurse Miller was dispatched back to Nonnatus House to ask Nurse Lee (acknowledged by all as the superior musician) to transpose it into a simpler key, Timothy was far from convinced he would ever be able to play it at more than lumbering pace.

From Akela came news: they had the name and address of a man who had been with his father at Dunkirk. He had been wild to write the letter there and then, to post it at once, but she had cautioned him. "He might not want to recall ghastly things like the war and might not even remember your pa at all. You need to be jolly careful." Instead they planned the letter, listing what all needed to be included, and he was commissioned that night to write a version which she would check the next day.

Then had been the return to the rehearsal, now working on a scene where Gary Schofield not only knew neither lines nor moves, but seemed incapable of remembering what it was even about. He stood smirking, while Fred patiently tried to help him remember and the other boys grew increasingly mutinous. It was Jack who was told off for yelling "Are you just stupid?" after Gary came on from the wrong side for the third time, but honest Timothy knew that he had thought it too and suspected from Peter Williams' scowl that their triumvirate was entirely united in irritation. Told to go and play while Fred persevered with the breathing furniture who was his lead actor, they decided that playing outside on Jack's bike, even in the cold, was preferable to endless shushing indoors. It was not unenjoyable, reflected Timothy; however with a letter to write and the appalling piece to master, it was a terrible waste of time, more painful given the shock realisation he had had that morning: this was the last Saturday of 'Us Two'.

He was brooding on this, only half watching, when it happened. After taking initial turns on the bike, they had devised a circuit, using caps, scarves and gloves to mark out elaborate chicanes. Timothy's modest time was thrashed by Jack and finally it was Peter's turn. Nervous after Jack reminded him that the bike had been a gift from Akela, whose husband was a copper and knew what was what with boys who damaged property, Peter wobbled up to the sharpest turn, where the front wheel slipped on the edge of a patch of ice still unmelted from the previous night. The bike slid out of his control and collided with the wall, as Peter landed on the ground with a loud shriek.

The two men quickly reappeared from around the corner, abruptly stopping when confronted with tears, recriminations and a bloody, mucky knee. "Are you alright?" asked the taller one.

There was something oddly familiar about him, Timothy realised, and looked more intently. The men remained frozen, awkwardly muttering, each nudging the other to help the crying child. Why were they waiting, thought Timothy, apparently panicked by these exotic vicious creatures called boys, instead of helping Peter? Was that not what adults did? His father might be hasty, brusque, occasionally angry, but he would never just stand, expecting somebody else to act. Timothy had wondered initially if the man was a colleague of his father's. Now that seemed impossible.

It was the friend who eventually took the tentative step forward, offering an almost clean handkerchief to the still snivelling Peter. "Fell off your bike?"

Jack, examining the frame of the bicycle for scratches, exclaimed scornfully, "It's my bike! Don't be a big girl's blouse, Pete!"

At this, Peter looked even more miserable, cowering into the handkerchief and whining it might be worse than it looked, while the blond man knelt beside him and uprighted him.

Timothy hunched down and peered at a sizeable scrape on Peter's leg. "It's only a graze," he said dismissively, until Peter's bubbling eyes recalled to him a similar reaction at the same diagnosis and he added more kindly, "but it needs a bandage and to be cleaned." He heard a snort behind him. The other man's twitching smile made the face even more recognisable.

"'is dad's a doctor!" said Jack hotly. "'e knows about this stuff."

"Sorry, we're just architects," said the kneeling man soberly to Timothy, adding to his friend, "Do you think we should get one of the girls round from Nonnatus House to have a look?"

"Akela's inside. She's a Nonnatus nurse," offered Jack.

"Is that Chummy?" When Jack shrugged his shoulders, he expanded. "Nurse Noakes?" The boys nodded. "Go and get her."

As Jack vanished, Timothy turned to the tall man. At the name Nonnatus House, he had remembered. "I know you," said Timothy. "You're Nurse Lee's friend. She was sitting on the back of your scooter." He had his back to the blond man and did not see his attentiveness, only the dark haired man's mild embarrassment. "She was hugging you."

"How do you know Je – Miss Lee?"

"She works with my dad. He's a – "

"Doctor," the man interrupted. "Of course. Your friend said."

"I know her too, though," Timothy added, quickly. "She'll be here soon, actually. She's rewriting some music for me at the moment."

Whether the shared acquaintance made formality impossible, or the man simply felt foolish that he alone was still standing, he decided to join them, crouching next to Peter. Now starting to calm, the boy stopped whimpering and began to stare at the camera dangling from the man's neck. "I like your camera," he said.

"Thank you." The man gestured to it. "I could take a picture of the two of you if you'd like?"

There was a novelty to this. Forgetting one's grazed leg and the other's general gloominess, the boys were posing when the hall door opened.

"Peter Williams! What have you done to yourself? Careering into walls and destroying the fabric of the district?" Although she spoke briskly, nobody was deceived or surprised by the gentleness with which Chummy received the child from the blond man.

"Hello, Chummy."

"What ho, Jimmy!" She nodded to the other man. "Hello, Alec."

"Letting your charges charge around a bit too much, perhaps?" He laughed at her baleful groan.

"It's 'is fault," said Jack, aggrieved. "Me and Timothy could ride it alright!"

"Jack Smith, be quiet. You're in danger of being demoted from an alderman to a cockney wide boy. Bagheera needs you inside now, so in you go, pronto! Timothy, you've still got a few minutes." Jack sauntered inside, nursing the remnants of his dignity, as Chummy shepherded a limping Peter away.

Timothy alone was left. He pondered whether he should return to the warmth of the hall and somehow start drafting his letter. Had it been to Uncle David or Uncle Kenneth he would have done; if it had been a letter to Shelagh, a letter promised but as yet unwritten, he would have been gleeful, adding details about Fred and which sections of the pantomime she would most like. But his brain was too fretful for this strange request to a faceless unknown. Better to leave it until the long stretch of evening, punctuated by kind enquiries from Mrs. Harrison, and sitting opposite the blank emptiness of his father's armchair. Instead he listlessly collected the various items of clothing which had marked out their racing track, damp and cold and slightly soiled.

The men had not left either, although they no longer contemplated the building. They were talking a few yards away, quietly, yet not so quietly that they couldn't be overheard. "There's something odd about the damp course on the side wall I want to check again. You go, though, Jimmy."

The blond man's look was ironic. "Damp course? Alright. Say hello to her from me."

The way the dark man did not entirely meet his friend's eye was not quite the same as the expression Timothy had seen on his father's face some weeks earlier when Timothy asked why he was taking so long to shave when they were supposed to be collecting Shelagh. It was similar enough, however; and when the man turned after seeing his colleague off, apparently now unbothered about any damp wall, he found a small boy curiously watching him.

"Are you waiting because you want to see Nurse Lee?" Timothy asked bluntly.

As the man admitted it was, he dreaded where the interrogation might be about to go. When he had imagined himself questioned about his intentions towards Jenny, it had been by a nun, by turns stern and sympathetic, not a boy, young, inquisitive and unexpectedly astute.

Part of Timothy wanted to ask the question the man expected most, but a muddle of voices in his head warned him not to be rude: an old mixture of his mother's cadences and his father's words, now with something new chuckling underneath. Instead, he changed the enquiry. "How do you know her?"

"My friend Jimmy, who was just here, introduced us. They've known each other since they were children, almost as young as you!" Suddenly the boy seemed self-conscious and twisted his cap in his hand, but he still peeked at him, shyly smiling. "What did you say she's doing for you?"

"Re-writing music," Timothy explained. "I've got to play it on my violin in our pantomime, but it's too hard. Nurse Miller's playing the piano for the pantomime, but Nurse Lee's much better at music, so she's going to get her to rewrite it."

"Is that why you're here? Are you rehearsing?"

"Yeah," he sighed, disconsolately. "I wish we didn't have to."

"Not enjoying it?"

Timothy scrunched up his nose. Although he was cold and frustrated, it was not true that he didn't enjoy the pantomime. "Usually I do," he started. "It's Dick Whittington and I've got a really good part as well as playing my violin because I'm the cat. The cat and the fiddle. It's a joke, do you see?" The man laughed. "But I've got loads of things to do at the moment and I've hardly been needed this morning and it's really boring and I wish I – ." He stopped, embarrassed at what he had been about to say.

"It's not much fun working on Saturday mornings," sympathised the man.

"My dad does it all the time and Saturday night too," Timothy commented. "He's always working, except he's not this morning, which makes it more annoying. My dad's Dr. Turner." Holding out a solemn hand to be shaken, he introduced himself. "I'm Timothy Turner."

"Alec. Alec Jesmond," said the man, taking the hand gravely. "Pleased to meet you. What makes what more annoying?" he asked.

The hand was quickly withdrawn and thrust into a pocket, as Timothy looked away from this man he barely knew. "Nothing," he mumbled. "We just do stuff together on Saturdays sometimes."

Alec did not press against the newly erected reserve, instead returning to his camera to check the number of pictures left and shooting the underside of some rusted guttering. It was while he was rolling the film on that Timothy spoke again, curiosity again greater than momentary shyness. "What are you taking pictures of?"

"Damaged bits of the building. Not very exciting. It's for work. I've taken some before, but there wasn't enough detail of the problems."

"Like what?" For ten minutes Alec answered Timothy's every eager query, pointing out bomb damage and crumbling features until finally handing over the precious camera and helping the child take the final shot himself. "I wish I had a camera," said Timothy.

"Do your parents not have one? Maybe you could borrow it?"

"My mum's dead," he said, without looking at Alec. He was used the flash of mortification and pity on grown-ups' faces; he did not want to see it again. "My dad does, but he'd want to know what I want it for and it would get a bit tricky."

"Why?" asked Alec. "Do you want it for something particular?"

Timothy scuffed the toe of one shoe. "A picture of my dad. All the photographs of him are really rubbish or really old," he explained. "He's getting married again soon, just before Christmas, and I know there'll be lots of pictures taken then, but I'd like to get one of just him now."

Alec paused, uncertain. He wished Jenny would appear. "I see. Is that as a reminder of things at the moment before they change?" he suggested.

Timothy frowned, slightly troubled by the words. They were close, so close, to the heaviness he had felt that morning when his calendar told him this was the last Saturday of confidential "man-to-man chats" accompanying the board game league and plates of fried bread, and that even these would be truncated by duty, his in the morning, his father's later. He had tried to quell his dismay: it made no sense. He was counting the hours until Shelagh's train would draw into King's Cross and his Saturdays with her were treasured memories, no less joyful than those with his father, while he hugged himself every time he anticipated the meticulous plan for next Saturday finally coming to fruition. Yet he did feel gnawed by the dull ache of something. It was not sorrow any more than he felt sorrow at losing his baby teeth or his first bicycle; but there was a murky worry festering within him.

That anxious confusion, however, was far from linked with wanting a photograph of his father; the sweet reason was entirely the reverse. Eventually he replied, uncertainly. "No, as a Christmas present for Shelagh. That's Dad's fiancée," he explained, with careful elocution. "She's in Scotland at the moment and just before she went, she and Dad realised they didn't have photographs of each other and she was really upset about it. If I'd a camera, I could take a picture of Dad for her."

There was a boyish chuckle of relief. "I see. You get on well, then?"

"Yes, of course. She's brilliant," said Timothy, puzzled. "I've known her for ages and ages. Dad thinks she liked me before she started liking him." Leaning against some railings, he contemplated Alec. "Did you think I wouldn't like her?"

"No, no. It's great you like her," replied Alec, reluctant to explain. He had been standing opposite Timothy; now he joined him. "I just wondered how you felt about getting a new mother, especially if you've got things you do specially with your father. People don't always like change," he added, looking up at the building, the red letters of the notice glowering on the door.

Timothy said nothing, his head on one side. They were still standing thus, alongside one another, when they heard a sharp tap of shoes and a flurry of skirts and Jenny Lee arrived. She looked tired, her face clean of make-up, as though dragged from sleep, until her eyes brightened as she saw Timothy was not alone.

"Alec."

"Hello, Jenny." He stepped towards her, until he was only a few paces away.

Timothy thought he was now an expert in observing couples and here was the same intent gazing. But they were coy, almost nervous, Alec's smile too bright, while Jenny looked away, down and back as they exchanged pleasantries. How different from his father and Shelagh, he thought. His father grew nervous before seeing her, smoking and fiddling with things, ceaselessly tapping on the steering wheel of his car if he was driving, sometimes silent or irritable, while she withdrew into herself; but once together something was released and they were entirely themselves, perhaps even more themselves when together than they seemed capable of when apart. And when Jenny's eyes flickered to Timothy in embarrassment, he felt uncomfortable in a way he had never previously done: with his father and Shelagh either he was part of the moment of meeting or, on a tiny number of occasions, they were so absorbed by each other that for a instance he did not exist in their world. Those moments were rare and startling, but never awkward as this was. As quietly as he could, he tried to slip back to the hall.

Jenny, however, stopped him. "Hello Timothy. Here's your music. I've put it into G major, which should be much easier for you."

"Thank you, Nurse Lee." She smiled prettily. "I'll go and practise it now," he continued unsubtly. "Thank you for letting me take a picture on your camera, Alec. It was really good."

"It's a pleasure," said Alec. "You can have a copy, if you'd like?" Timothy nodded with such enthusiasm that he made a second offer. "As you don't have your own camera, would you like me to take a photograph of your father for you? Or maybe your father's fiancée would prefer a picture of you and your father together? I'd be more than happy to." Although he could see Jenny' reaction from the corner of his eye, it was not the only reason for the suggestion.

"Really?" Timothy beamed. "That'd be amazing. I don't know what she'd like more though."

"I can always take both and you choose. You could keep the other one for yourself."

"Are you going to have a photograph taken as a present for Shelagh?" asked Jenny. "That's lovely! It should be of both of you. She'll treasure it."

"We're having dinner with Sister Julienne on Wednesday. Can we do it then?"

Alec nodded, well rewarded by Jenny's enthusiasm. "I hope the rehearsal ends soon and you get to do some of your 'stuff' with your dad!"

Timothy grinned. "Thank you!" Then he stopped, serious again, wondering if Alec, so much closer in age to him than to his father, could help him once more. "Alec, if you'd had one afternoon with your dad when you were my age and it was just the two of you and sort of special, what would you have done?"

A muscle in Alec's cheek jerked. "I don't really know, Timothy. I never did special things with my father when I was your age. It was the war and he was away with the RAF. By the time he came back, I'd got used to things with just Mum and was a bit old for special afternoons. I'm sorry. I'm sure you'll come up with something, though."

There was a wistfulness in Alec's tone. It explained the sudden leap he had made to remembering things before they changed and it echoed in Timothy. He thought about it as he began laboriously practising the hornpipe. He still thought about it that evening while feverishly writing his letter, painstakingly copying the smudgy draft onto cream coloured writing paper purloined from his father's study.

It had rained in the afternoon and they had stayed at home, content to play chess and listen to records while Dad laughed at the accounts of Gary Schofield's ineptitude. While records were scattered on the sideboard for him to play that evening and the chessboard was still on the table, its desultory veterans of battle crowded around it, his father was at the maternity hospital now. Only Mrs. Harrison occasionally pulled him out of his silence.

Dad had once explained to him the difference between being clever and having a good memory: people could either remember things or they couldn't; being intelligent like Uncle Kenneth was about putting different bits of information together and making deductions. That was what diagnosing was. Now he tried to diagnose himself: why did he long for Shelagh's return and dream of life after the wedding, yet suddenly cling more and more closely to familiar routines of affection and loneliness, both loved and hated? Towards the end of the rehearsal he had planned a perfect afternoon with his father in his mind, but then when his father collected him ten minutes late, he had been petulant and tetchy. 'Before they change'. He remembered Alec's words. As he looked over to where old photographs of his father and mother and himself were displayed, he slightly shook.

"Timothy, love, are you alright?" Mrs. Harrison's voice and manner did not change. They never changed, like warm and comfortable slippers that were moulded to your feet.

"Yes, thank you," said Timothy. "Tickety-boo, as Dad says."

"It's quite chilly, isn't it? Let's have another bar on the fire. I don't know what my friends in Yorkshire would say to see me now – complaining about cold and burning away money! Becoming far too much of a southerner, these days!" She kept watching him as she crossed the room until she heard a quiet snigger. "Have you finished your letter?" He had not divulged the finer details, but it had been too hard to hide completely what he was doing when she caught him creeping into the study to find the writing paper.

"Almost. Last paragraph."

"Is that you almost all done now with your Best Man preparations?"

"Yes. There's only one thing where I'm really stuck. Do you know where men can get nice clothes?"

Mrs. Harrison blinked as she looked up from the fireplace. "Not really, dear. I could ask my Andrew if you'd like?"

Timothy sighed quietly. He had met Mrs. Harrison's son, an open-hearted, pleasant man, in clothing as drab as his father's. Very few people he knew ever dressed like people in newspapers or the magazines his mother used to read; only Auntie Louisa and, when she wasn't in uniform, Nurse Lee. Then his mind began to reverberate, again piecing together information. A woman who was pretty and stylish. A sympathetic man who was her friend. Slowly Timothy started to grin; now he knew how to find out where to buy clothes.