Anna took the jewellery boxes from the cases laid out on the chaise longue at the foot of Lady Mary's bed, stacking them on the dressing table ready to be put away in their proper places. As she turned, she caught the edge of Mary's correspondence folder, sending it spilling off the table, papers floating out and scattering on the floor.

Anna sighed. She was so tired today after the long journey home; this was exactly the type of thing she didn't need when all she wanted was to go back to her cottage with her husband and put her feet up.

She got down on her knees, collecting the papers, smiling as she picked up one starting, 'My dearest Tom'. Then she froze, staring at the paper, quite unable to believe what she was seeing. Snippets like 'I imagine you kissing every inch of my skin', 'every time I touch myself, I think of you' and the utterly unambiguous 'I miss the feel of you inside me, filling me so gloriously' danced in front of her eyes.

'What do you think you are doing?' came a furious voice from the door.

Anna rose guiltily to her feet as Lady Mary came hurtling towards her to snatch the letter from her hands.

'I'm sorry, milady. I knocked your folder and it fell on the floor.'

'So, you thought you'd read my private correspondence?' Mary hissed, embarrassment fuelling her fury.

'No, of course not. I would never do that. Not deliberately.'

'But you were reading it! I saw you, Anna!'

'I wasn't reading it, exactly.'

'No?' Hope that her secret might yet remain undiscovered flared in Mary's chest.

'But I did see some phrases that were not meant for my eyes.'

'Oh, God!' Mary pushed past her maid, still clutching the letter, to sink onto the edge of the bed, her shoulders slumped, her face pale except for crimson spots high on her cheeks.

Anna quickly crossed the room to shut the bedroom door before returning to stand before her mistress.

'You must think me an awful harlot,' Mary said quietly.

'Of course not, milady.'

Mary shot Anna a sceptical look. 'Come off it, Anna. You of all people know what a sinful creature I am.'

Anna looked down at her feet, choosing her words carefully. 'You and I have been through a lot together, milady. I won't lie and say I'm not shocked by what I saw, but I don't think badly of you.'

'Really? A widowed woman writing sexually explicit letters to the last man on earth she should be writing such things to?'

'Can I be honest, milady?'

'You may as well be, Anna.'

'Although the contents of the letter were… unexpected, I'm more shocked by who you're writing these things to.'

Mary looked up at her maid, a flush stealing up her neck.

'You and Mr Branson?' Anna asked, curiously.

'Now you know my darkest secret,' Mary said, flatly. 'I've been having an affair with my brother-in-law.'

Anna eyed her thoughtfully, putting together the moodiness and excess of temper tantrums she'd seen from her mistress over the last few months. All since Mr Branson had gone to America.

'You must miss him a lot, milady.'

Tears flooded Mary's eyes and her face crumpled as she clapped her hand over her mouth, trying to hold back a sob.

'Oh, milady!' Anna stepped forward and put her arms around Mary's narrow shoulders, hugging her.

Mary let Anna hold her, sliding her arms around her maid's waist as she finally let herself cry. Anna held her and rocked her, shushing her and trying to soothe her until, eventually, Mary calmed down a little. She let go of Anna and dashed the tears from her cheeks. Anna pulled a handkerchief from her pocket and gave it to her.

'I'm making a spectacle of myself,' Mary said, dabbing at her eyes and wiping her nose. 'I'm so sorry, Anna.'

'You have nothing to be sorry for, milady.'

'It's just that nobody knows about Tom and I, and it's been so very hard to bear it on my own.'

Anna sat down beside Mary, picking up her hand and clasping it between her own. 'Do you want to talk about it? It might help to share your feelings with someone else. And you know I won't breathe a word to anyone. Not even Mr Bates.'

'I know you won't. You already hold so many of my secrets. You have never let me down and I am endlessly grateful for that.'

'Then let me hold another secret if it will help you feel better.'

Mary nodded, unsure of where to begin.

'You and Mr Branson,' Anna repeated, wonderingly. 'I didn't see that coming. I mean, I knew you were close but not…'

'…that close?' Mary finished for her.

Anna smiled. 'No. So when did it start?'

'Last May. After that awful week in Liverpool with Lord Gillingham. Yet another of my dark secrets.'

Anna looked at her in surprise. 'May? And I suppose it ended when he went to America?'

'Yes,' Mary nodded, miserably.

'Heavens. I'm not much of a lady's maid if you were carrying on with Mr Branson for seven months and I never noticed a thing.'

Mary gave a small smile. 'We were discreet. And you were preoccupied with all that nasty business with the police for most of that time.'

'Still, I must not have been very observant. How did it come about?'

Mary blushed. 'Well, you remember how disappointed I was with Lord Gillingham?'

Anna nodded.

'I found myself more than a little… frustrated,' Mary confided, a little awkwardly.

Anna's eyes widened, but she nodded again. 'I can understand that.'

Mary raised a dubious eyebrow at her.

Anna gave a small shake of her head and a slight roll of her eyes. 'I'm a married woman, milady. I have spent time away from my husband and our marital bed. I understand what you mean.'

Mary relaxed, relieved that her maid did know what she was talking about. 'The situation was making me terribly moody. and I may have blurted it all out to Tom one day and he may have suggested we take care of each other's frustrations.'

Anna's eyebrows slid up towards her hairline. 'Did he now?'

'I admit it shocked me at first when he said it, but when I thought about it, it made perfect sense. We were both widowed and neither of us were ready to marry again, but we both had physical needs we were neglecting. And we knew we could rely on each other to be discreet. So, we began sleeping together.'

Anna nodded as if she heard this kind of thing all the time. 'That must have been quite exciting, keeping it a secret like that.'

'Oh, Anna, it was wonderful! Our arrangement made us both happier and more relaxed. He was…' Mary paused and corrected herself. 'It was perfect. The perfect solution to our problems.'

'But I don't understand. If you were so in love with each other, why did Mr Branson go to America?'

Mary shook her head. 'Oh, no, we weren't in love. It was just, well, not to put too fine a point on it, it was just a sexual thing, not a love affair. Tom can't put his life on hold for that.'

Anna gave Mary a sympathetic look and squeezed her hand. 'Oh, milady. You can be honest with me.'

'I don't know what you mean,' Mary said, evasively, her eyes skittering away from Anna.

'I think you do. You love him. I can see it in your face when you talk about him.'

'Of course, I love him. He's my best friend. But I'm not in love with him.'

Anna just gazed at her with that same understanding, sympathetic look in her eye.

'I'm not,' Mary insisted.

'Milady, you've been miserable since Mr Branson left. I've noticed it, but I didn't know quite why you were so down. Now it all makes sense. You don't have to be honest with me if you don't want to, but you should be honest with yourself.'

Mary closed her eyes briefly before nodding her head and meeting Anna's gaze. 'All right. All right. Yes, I think I might be in love with him. But I can't be, Anna. He was married to my sister, for heaven's sake! How can I admit to being in love with him?'

'The heart wants what it wants. Besides, he was Lady Sybil's widower when you went to bed with him. Why is that any different to loving him?'

'Because loving him changes everything! I can't step into Sybil's shoes. Mama and Papa couldn't bear it, I'm sure.'

'Lord and Lady Grantham would be surprised, I don't doubt it, but they love you and they are very fond of Mr Branson. They'd want you both to be happy.'

'We'd be shunned by polite society.'

Anna smiled at that. 'You forget, milady, I know the Tom Branson that used to talk politics and rebellion downstairs. I doubt if he gives two figs for polite society.'

'Maybe not, but I do.'

'I admit it might not be easy to bring your relationship out into the open, but if it makes you happy – if he makes you happy – isn't it worth it?'

Mary was silent, weighing that up, before speaking again. 'There's one obstacle we can't overcome, Anna.'

'What's that then?'

'I don't think he's in love with me.'

'Has he told you that?'

'No.'

'Then you don't know that's true.'

'I do.'

'How?'

'He left, didn't he?'

Anna looked at her lady in consternation as a tear slipped down Mary's cheek.

'It's a mess, Anna. You're right, I am miserable without him. I lied earlier. I don't think I'm in love with him, I know I am. I almost told him so twice, once when we were in the Lake District and again right before he left for America.'

'Then why didn't you?'

'Because of Sybil. He loved her so very much. I could never replace her in his heart.'

Anna gave Mary such a look of sympathy, she could hardly bear it. But now she'd started, she couldn't hold her words in.

'It's hopeless, though. I'm longing to see him, but I know he won't be back for months, maybe even years. But I'm already dreading that too. I don't know how it will be when he visits Downton, but I expect it will be horribly uncomfortable. There will be this thing there between us that's in the past for him, but I suspect not for me because I'm very much afraid I don't know how to get over him.'

'Oh, milady,' Anna whispered, putting her arm around Mary again, patting her gently, as she began to cry once more. Mary gripped Anna's hand, making a visible effort to get her emotions back under control.

'This is a novel situation for me,' she said ruefully. 'I'm usually the one breaking hearts, not having mine broken. And I only have myself to blame. If I'd never said anything to him in the first place, I doubt it would ever have happened.'

'Do you regret it then? The affair with Mr Branson?'

Mary shook her head fiercely. 'Not one single second of it.'

Anna looked thoughtfully at her mistress. 'It sounds like it was quite a passionate affair.'

Mary looked Anna square in the face, too far down the path of honesty to hold back now. 'It was. It was like nothing I've ever known before.'

'Are you quite sure he doesn't love you back?'

'Well, I haven't asked him if that's what you mean. I'm not a glutton for punishment.'

'But your letter… was it the first letter of that nature you've written to him?'

'No, there have been quite a few others.'

'And does Mr Branson respond in kind?'

Mary slanted a glance at Anna. 'Yes, he does. In fact, between me and you, he's much better at it than I am. He's far more… descriptive.'

Anna's eyebrows shot up. 'Really?'

'Yes. Let's just say he has a definite way with words,' Mary said, a faint blush tinging her cheeks.

'Well, then I have a question, milady.'

'Go on.'

'If it's all over between you, and Mr Branson is moving on with his life, why would he write passionate letters back to you?'

'I don't know. Maybe he doesn't want to embarrass me by not replying.'

'Milady, there's more embarrassment to be had if one of his letters goes astray, especially if they are as detailed as you say. Isn't it more likely that he's replying because he feels the same way as you?

Mary stared at Anna, pensively. 'I hadn't thought of it like that. Do you really think that could be the case?'

'I don't think we can rule it out.'

'Good heavens, Anna, that's certainly food for thought. There's just one thing wrong with that supposition.'

'What?'

'If he loves me, why did he leave?'

'That I can't say, milady. Except maybe he thinks the same as you, that his love isn't returned. Perhaps he left to protect his heart.'

Mary shook her head, releasing Anna's hand and rising to her feet. 'I rather think you've been reading too many romance novels, Anna.'

'Maybe, but I do think it's odd that he's writing these letters to you if he's set on moving forward with his life in America. It just doesn't make sense to me to hang on to the past if you're making a new start and looking to the future.'

Mary sat down at her dressing table, turning Anna's words over and over in her head.