a boy who is on a ship, being evacuated (WWII, I think) and makes friends with another boy who is a card shark. The ship is bombed or torpedoed or otherwise wrecked, but the hero survives. In adult life, he makes contact again with his friend from the ship

[Santa]

I'm reading Cat's Table now and it brings to mind another book I've read, about a boy who is on a ship, being evacuated (WWII, I think) and makes friends with another boy who is a card shark. The ship is bombed or torpedoed or otherwise wrecked, but the hero survives. In adult life, he makes contact again with his friend from the ship, who has thrived and from whom he needs a favor. I have a vague recollection that the ship is sailing to or from the Indian subcontinent and that his friend is Indian.

[Ayshe]

This needs to be moved to the Unsolved folder.

Old Filth maybe? I vaguely remember something like that but it's been a while since I read it.

[Santa]

Since I have read (and enjoyed) Old Filth, that could well be it.

[Kris]

Santa, I moved your request to the Unsolved folder because you're looking for a specific book.

Here is the Google Preview of Old Filth by Jane Gardam -- https://books.google.com/books?id=ILA...

I edited your title/header to "boys..." Please add more plot details and genre by using the "edit" link on the desktop website (not mobile app). Someone is more likely to recognize your book. Just ask if you'd like help with this.

Tips for posting a book request: https://www.goodreads.com/topic/show/...

[Ayshe]

Santa wrote: "Since I have read (and enjoyed) Old Filth, that could well be it."
Let us know when you confirmed or disproved that.

The one I'm remembering is probably his meeting with Albert Loss when he is evacuated on ship for Singapore: https://books.google.com/books?id=TWm...
It appears (I don't remember much :) ) the port falls to the Japanese as the ship approaches — and Feathers is taken back to England but Albert decides to stay there.

[Lobstergirl, au gratin]

Santa, are you still looking for this or did you find it?