I enjoyed "I'll Never Forget You" with Tyrone Power and Ann Blyth more than I did "Berkeley Square" (the latter seemed rather creaky to me). It's been many years since I saw either one, and I'm not sure which is actually closer to the original play written by John Balderston, which I enjoyed very much. If I remember correctly, the Tyrone Power version has the hero as a scientist, which seems like quite a departure from the original play; but in a way that's an interesting choice given that the source for the play was an unfinished novel by Henry James that I've thought may in turn have reflected James's friendship with H.G. Wells.
From what I recall, it's not just the time travel story that could have inspired the DS storyline but the fact that, in the original play at least, the main character has a deep-seated fascination with his ancestor and so travels back in time to the world and life of his own ancestors.
I don't recall whether "I'll Never Forget You" kept that idea or not ... it would be fun to see it again.