Thank you so much to everyone reading and especially to those leaving reviews. I wish I could reply to your comments! I do like seeing your theories. You make my day!

It took every ounce of Mary's considerable social skills, honed over a lifetime, to keep a lid on her emotions as Tom and Sybbie left Downton. She didn't have to stay completely emotionless – that would have been impossible – but Mary was very afraid that if she let herself go, she may never find her way back.

The whole affair was far from the stoic façade usually presented by the English upper classes. The day started badly with Sybbie having a meltdown after breakfast. Tom had already had several talks with her, explaining they were going on an adventure over the seas to America. She'd been fine with that until she finally grasped that morning that Donk, Granny, Georgie, Marigold, Aunt Mary and Aunt Edith weren't going with them and then the waterworks began.

Cora tried her best to calm her granddaughter, telling her how exciting America would be and that she'd meet new cousins and make new friends when she got there. For his part, Robert paced the room, distraught to see his beloved eldest granddaughter so upset. Eventually, Tom picked his daughter up, carrying her to the other end of the room, talking to her quietly.

Mary watched Sybbie calm as she listened to her father, tilting her head towards him then wrapping her little arms around his neck. If there was one thing she wasn't worried about, it was Tom's skills as a father and his ability to take care of his daughter without the support of nannies, servants or the rest of the family. Right from the start, he'd been the most hands-on father she'd ever come across, probably because his upbringing had been so different from her own, where parents took care of their children themselves. For a brief moment, she ghosted her hand across her abdomen, almost wishing he'd left a child in her, a child that could know the love of such a father.

After lunch, Sybbie said goodbye to her cousins in the nursery, leading to a tearful triumvirate of little people. Mary's heart broke a little as George held his hand out solemnly to Tom, who dropped to one knee to shake it, telling her son to look after his mother for him. When Tom held out his arms, George rushed straight into them, hugging his uncle tight around the neck. Mary bit her lip, blinking back tears.

Downstairs, Edith and Cora fussed over Sybbie, making sure she had everything she needed for her train journey as Robert hovered, not quite knowing what to do.

As Tom said his goodbyes to a teary Edith, Mary crouched down before Sybbie, hugging her tight, before pulling back to smooth the child's hair and straighten her hat.

'You're going to have such an adventure, darling. It's going to be quite something. Now, promise me you'll be a good girl for your father. You must be very grown up and look after him as much as he will look after you. Every night when you go to bed, make sure you give him an extra kiss from me.'

Sybbie nodded, gravely. 'I will, Aunt Mary. I promise.'

Mary kissed her niece's brow and looked up to see Tom watching her over Cora's shoulder as he hugged his mother-in-law. She took Sybbie's hand and they walked over to Tom just as her father shook hands with him, placing a paternal hand on his shoulder.

'I fear I shall miss you dreadfully, Tom,' she heard Papa say. 'You have been my ally in a houseful of strong-willed women. Who will I take refuge with now when it all gets too much?'

Tom chuckled, smiling warmly at his father-in-law. 'You don't need an ally, Robert. Just take good care of our girls.'

'I will. And you must take equally good care of my darling Sybbie. She is very precious to me. Cherish her.'

'I promise you I will, with every breath in my body and every beat of my heart.'

Robert nodded, still grasping Tom's hand. 'I know you will. Look after yourself as well, my boy. I find I have grown very fond of you.'

Tom smiled at him, affection for the older man written on his face. 'You take care too, Robert.'

Robert cleared his throat, visibly buttoning down his emotions, and turned away, reaching out his arms to his granddaughter. 'Come here, darling,' he said, gruffly. 'Give old Donk one last kiss and a big hug.'

Tom watched him gather Sybbie into his arms, raising her up to be on eye level with him, Cora and Edith crowding round them, giving Robert quiet support as he said his goodbyes.

Tom met Mary's eyes and crossed quickly to stand in front of her. They'd said a private goodbye upstairs away from prying eyes, but this was to be their public farewell.

Mary reached out to brush a stray hair from his shoulder. 'Well,' she said, 'this is it then.'

'Yes.'

'Promise you'll write as soon as you can.'

'I promise.'

They locked eyes then Tom stepped forward and pulled her into a tight hug. Mary wrapped her arms around his neck, squeezing her eyes shut, willing herself not to start crying.

'Take good care of yourself, Mary,' he whispered in her ear. 'And remember, ní mar a síltear a bítear.'

Mary clamped her lips together, holding back a sob as she recognised the Gaelic words.

Too soon, he was releasing her. He leaned forward to kiss her on the cheek, exactly as he had done with Edith and Mama.

'Goodbye, Mary.'

'Goodbye, Tom.'

As Tom and Sybbie got into the back seat of the car, Mary felt someone take her hand and squeeze it gently. She looked to her right to see her mother standing next to her. Cora gave her a look of sympathy that almost broke Mary's hard-won composure.

The family stood together, waving as the car drove off, taking Tom and Sybbie away to their new life.

'Well,' said Robert, his voice somewhat unsteady. 'I think we might all need a drink after that.'

'No more alcohol for you, my darling,' his wife reminded him gently. 'You know what Dr Clarkson said.'

'Hmm, then I suppose a strong cup of tea will have to do.'

As her parents and sister walked back into the house, Mary stood watching until she could see the car no more before following them. Carson waited in the doorway, watching her with sorrowful eyes.

'It's for the best, milady,' he said in a low voice as she passed him.

Mary stopped dead, staring blankly into the empty hallway. 'No, Carson, I don't believe it is.'

Then she raised her head, wiped the tears from under her eyes and went to put a brave face on in the library with the remaining members of her family.