This is a long shot, I know. But here goes.
My great aunt has a photograph of her grandfather (my great x2 grandfather) which was taken by the London Portrait Company of 68 Cheapside.
It has a negative number on the back (52971).
Does anybody know whether the London Portrait Company still exists somewhere; or if not, what became of its negatives and whether they are still held in some photographic archive somewhere?
(I suspect that the answer is that the negatives, if they survived that long, were probably destroyed in the Blitz ... but this is not inevitably so by any means!)