Osgood kept her bright smile firmly in place as Kate rushed around the living room grabbing the things she would need for the day. The delicious breakfast the brunette had made her girlfriend in honour of her birthday had made Kate late enough that she didn't question the fact that Osgood hadn't decided to join her at UNIT Headquarters on her day off. Instead, the younger woman was sitting calmly on the sofa, watching her girlfriend hurrying around gathering her belongings.

With a brief kiss on the cheek, Kate left the house, letting the front door bang shut behind her. The second she was gone, Osgood was on her feet and heading into the kitchen to begin the first stage in Operation Birthday. A couple of minutes later, the front door opened again. Osgood froze for a moment, holding her breath.

"Os? It's just me. She's gone, right?"

"I'm in the kitchen!" Osgood shouted back, straightening up with an armful of bowls and various other implements. "I hope you're prepared for this. Baking is a serious business."

"You are kidding, right?" Emily asked, arching an eyebrow and looking eerily like her mother. "It's just cake. Some flour, butter, a few eggs… maybe some coco powder. Bam. Done."

With a chuckle, the older woman shook her head and turned back to the kitchen table, which was almost impossible to see under the mountain of ingredients and equipment. "An ordinary Victoria sponge, yes. But we're going to make Kate's favourites; Irish cream tiramisu, lemon meringue and macarons.

"Wait… what?" The teenager looked terrified at the prospect. "I'm not sure I–"

"Don't panic; it'll be alright. I've got my Nigella and my Mary… we'll be absolutely fine." Osgood assured her, holding up two recipe books. "As long as we follow the wisdom held in these pages, the deserts will be perfect."

"You're so weird…" Emily shook her head, pulling the Mary Berry book out of her grasp. "Tell you what, you do the cooking, I'll do the decorating."

Immediately Osgood's head shot up and her eyes narrowed. "Decorating? What do you mean decorating?"

"We can't have a party without some decorations." The girl shrugged. "Don't worry, I'm not going to blow up dozens of balloons or put up a piñata or anything. I'm just talking a few birthday banners… maybe moving some of the furniture out of the way to make a dance floor."

"A dance floor? How many people have you invited, Em?"

"Not many… Gordy and his new girlfriend, your parents, your sister and her family, a couple of mum's friends…"

"My parents? My sister?" Osgood pulled a face. "Why did you invite them?"

Emily grinned. "They're basically my step-grandparents, right? They should start coming to the family occasions."

"Please don't scandalise them." With a deep sigh, Osgood shook her head. "I don't think my mother would cope very well with most of your anecdotes."

"I promise I'll be on my best behaviour." She replied with a chuckle. "I'll leave you to it, then."

"No you don't!" Reaching out, the older woman grabbed her stepdaughter by the arm and tugged gently until Emily was standing beside her. "You're going to help me with this. We're going to bond over sieving and piping."

Emily groaned, but allowed herself to be tied into an apron and manoeuvred to stand at the kitchen table. The next few hours passed in a blur of flour and coco powder and rather a lot of good-natured bickering. Osgood got frustrated when Emily seemed incapable of following the simplest of instructions and Emily couldn't resist sampling almost everything that Osgood handed her. When, after being chided for the third time, the older woman caught sight of the teenager licking the wooden spoon yet again, Emily sighed deeply and prodded her in the ribs with the handle.

"You're the one who wanted me to help." She pointed out childishly.

"Yes, help… not eat all the ingredients."

"They're tasty!"

"They'll be tastier still when they come out of the oven." Osgood reminded her with a fond smile. "Now… washing up."

With another theatrical groan, the younger woman attempted to side step her stepmother and escape from the kitchen. Osgood was faster, blocking her route and handing her the dishcloth firmly. They made a big dent in the washing up quickly and soon the kitchen was back to its usual, pristine state.

They were just sitting down to a cup of tea when the timer on the oven pinged. Swatting Emily away, Osgood managed to pull the deserts out and set them aside to cool. She had given in to the teenager's demands that they also make a chocolate cake, although she had made it very clear that the decorating would be left up to her; Osgood wasn't a sprinkles and edible glitter type of girl.

"Right… now you have to come and help me decorate the living room." Emily announced as soon as Osgood was satisfied that her creations were cooling properly. At the expression of abject horror on the older woman's face, she laughed loudly. "Come on! It'll be fun!"

With an expression that said that Osgood thought that decorating for the party would be anything but fun, she allowed herself to be propelled into the living room and directed to push the sofa back against the wall. She raised her eyebrows, watching as the armchairs promptly followed suit and then the coffee table was carried out into the conservatory. Opening her mouth to speak, Osgood promptly shut it again as Emily stood in the middle of the room and spun slowly on her tiptoes, surveying the scene.

"Do you think we could move the bookcases?" She mused. "I mean… books about chess and Cold War strategy and gardening are hardly party standard, are they?"

"No, Emily. No… we are not moving the bookcases."

"But it's–"

"No."

"You are no fun." She huffed. Then a grin split her face and she leapt across the room, grabbing a pile of papers off the TV stand and handing them to Osgood. "What d'you think? She'll hate it, right? But in a totally 'that's hilarious' way?"

Peering down at the papers in her hands, Osgood couldn't help but agree that Kate would indeed hate the little surprise her daughter had arranged for her. It was, however, hilarious.

Emily had obviously raided the family photo albums for as many embarrassing photos of her mother as she could find and photocopied them, blowing them up into posters. There were childhood photos with tiny, wild-haired Kate grinning at the camera with various teeth missing. There were teenage photos of Kate sporting several questionable hairstyles and outfits. There were later photos of Kate with her children although, Osgood noted with interest, no photos of her ex-husband. She smiled fondly, spotting several very familiar photographs of herself and Kate.

"So? What do you think?"

"I think it's lovely." Osgood told her sincerely, smiling at the teenager. "Kate'll hate it and love it at the same time."

"That's what I thought." Emily nodded. "Right… let's get decorating then."

They were just balancing on the arms of the armchairs, attempting to blu-tack the happy birthday banner high on the wall above the fireplace, when the front door opened. Emily and Osgood exchanged a panicked look, carefully dropping down to stand on the floor and staring towards the hall. They were thankful that they had thought to close the door that linked the two rooms.

"Shh!" Emily cautioned, putting her hand over Osgood's mouth as Kate called her name. Nodding slowly, the older woman motioned that she wasn't going to reply and Emily dropped her hand to her side.

After a couple of moments of banging around, they heard Kate sigh loudly and emit a string of rather creative swear words, before the door opened and banged shut again. Wriggling slightly to pull her phone out of the pocket of her jeans, Osgood pulled a face as she realised she had missed several texts from her girlfriend, which explained why she was there.

'Did I leave my glasses in the hallstand? x'

'Os? x'

'I'm guessing you're busy… x'

'I'm going to pop home and look for them. Might I see you? x'

Wincing, Osgood showed the texts to Emily; careful not to let her read any of the previous messages from her mother. It wasn't that there was anything that would be particularly scarring to the teenager, but neither was Osgood about to give her any further information on her relationship with Kate.

"She's not going to be happy that I ignored her." Osgood murmured.

Emily shrugged. "She'll get over it when she sees what we've been doing." She motioned around them with a flourish. "Now… cake decorating time!"

"Did you get Grace's children to help you with the decorating?" Osgood's mother asked, looking at the chocolate birthday cake sitting on the side, liberally decorated with white chocolate stars and multi-coloured sprinkles.

Osgood snorted with amusement, catching the outraged expression on Emily's face as her mother mentioned her sister's children. "No, Mum, it was–"

"We got it like that." Emily told her bluntly. "It's cool… the handmade look."

"Ah…" Ruth nodded slowly, not looking as though she understood the concept. "What time are we expecting Kate?"

"Any moment now." Osgood replied, her eyes sparkling instinctively at the mention of her girlfriend. "She should have left the tower about half an hour ago."

"Then there's just enough time for Emily to fill me in on her summer plans."

Shooting Osgood a pleading look, the teenager was powerless to resist as the older woman propelled her away in the direction of her husband, ready to pump her for information about how she was planning to spend the months before beginning her next year at university. Chuckling lightly, knowing that Emily didn't really have any plans apart from hanging out with her friends and possibly finding herself a part-time job in a café or something, Osgood kept herself busy, refilling the bowls of snacks around the room.

She glanced at her watch every now and then, wondering how long Kate was going to be. When the time she should have arrived home came and then went, with no sign of the blonde, Osgood started to worry. Pulling out her mobile, she checked for any message to explain why her girlfriend was absent, but there was nothing.

"I'm just going to…" She waved her mobile meaningfully in the air, wordlessly explaining where she was going, before slipping out into the back garden and pulling the door shut behind her.

"Oh, thank God!"

Barely managing to stop herself screaming, Osgood whirled on the spot and found herself face-to-face with the woman she had spent the last twenty-five minutes worrying about. Putting a hand to her chest, feeling her racing heartbeat beneath her palm, she arched an eyebrow questioningly at Kate, who had the good grace to look apologetic.

"Sorry, Os." She winced. "I saw your parents' car on the drive and looked through the window. I was about to text you."

"I know you're not a fan of parties or people making a fuss of you, but Emily thought this would be nice." Osgood explained quickly. "We wanted to do something special for your birthday."

"I really didn't need anything like this. I would have been perfectly happy with a home cooked meal, some decent wine and something good on the telly."

Osgood smiled. "I know you would, but that's what we do every night. We needed to at least do something to mark the occasion. It's not every day you turn–"

"Nope, shhh!" Kate put her hand over Osgood's mouth, preventing her from saying the dreaded 'f' word. She had banned all mentions of her age. "You know you're not allowed to say it."

Grinning, the brunette kissed the fingers over her mouth, before tugging them out of the way. "Sorry, sorry." She glanced towards the kitchen door. "Now, are you ready to face your public?"

"I don't think so." Kate said childishly, wrinkling her nose.

"Well, tough." Her girlfriend laughed. "Emily has put a lot of effort into this party. Please compliment her on the cake; I think my mother actually deeply offended her when she asked if Grace's children decorated it."

Letting out a loud bark of laughter, Kate shook her head. "Poor Em."

"Poor Em indeed." Osgood agreed. "Now, come on… I want to get this party over and done with so I can give you your present."

Kate arched an eyebrow. "I'm assuming that means you can't give it to me in front of everyone?"

Osgood blushed crimson at the thought. "I don't think that would be a good idea, no."

"I think I'm going to like it very much, then." Kate told her, linking their fingers and allowing herself to be pulled into the house.