‘That’s exactly what he did – what we both did. It’s what he does with me now. I can keep him to that, if only your mother would trust me. If you worry him with keepers and cures he’ll be a physical wreck in a few years.’

‘There’s nothing wrong in being a physical wreck, you know. There’s no moral obligation to be Postmaster-General or Master of Foxhounds or to live to walk ten miles at eighty.’

‘Wrong,’ I said. ‘Moral obligation – now you’re back on religion again.’

‘I never left it,’ said Brideshead.

‘D’you know, Bridey, if I ever felt for a moment like becoming a Catholic, I should only have to talk to you for five minutes to be cured. You manage to reduce what seem quite sensible propositions to stark nonsense.’

‘It’s odd you should say that. I’ve heard it before from other people. It’s one of the many reasons why I don’t think I should make a good priest. It’s something in the way my mind works, I suppose.’

At luncheon Julia had no thoughts except for her guest who was coming that day. She drove to the station to meet him and brought him home to tea.

‘Mummy, do look at Rex’s Christmas present.’

It was a small tortoise with Julia’s initials set in diamonds in the living shell, and this slightly obscene object, now slipping impotently on the polished boards, now striding across the card-table, now lumbering over a rug, now withdrawn at a touch, now stretching its neck and swaying its withered, antediluvian head, became a memorable part of the evening, one of those needle-hooks of experience which catch the attention when larger matters are at stake.

‘Dear me,’ said Lady Marchmain. ‘I wonder if it eats the same sort of things as an ordinary tortoise.’

‘What will you do when it’s dead?’ asked Mr Samgrass. ‘Can you have another tortoise fitted into the shell?’

Rex had been told about the problem of Sebastian – he could scarcely have endured in that atmosphere without – and had a solution pat. He propounded it cheerfully and openly at tea, and after a day of whispering it was a relief to hear the thing discussed. ‘Send him to Borethus at Zürich. Borethus is the man. He works miracles every day at that sanatorium of his. You know how Charlie Kilcartney used to drink.’

‘No,’ said Lady Marchmain, with that sweet irony of hers. ‘No, I’m afraid I don’t know how Charlie Kilcartney drank.’

Julia, hearing her lover mocked, frowned at the tortoise, but Rex Mottram was impervious to such delicate mischief.

‘Two wives despaired of him,’ he said. ‘When he got engaged to Sylvia, she made it a condition that he should take the cure at Zürich. And it worked. He came back in three months a different man. And he hasn’t touched a drop since, even though Sylvia walked out on him.’

‘Why did she do that?’

‘Well, poor Charlie got rather a bore when he stopped drinking. But that’s not really the point of the story.’