I'm wondering if any clues might be teased out of the locations already discovered. I have no idea if the whole batch are related to each other in any way, but it might be worth considering.
There have been several of Great Yarmouth and Cromer. Then there seems to be some taken on a tour round the coast of the Highlands (Tain, Keiss Castle, Thurso, Brora, Bonar Bridge). There is the group associated with the Hanbury & Clifton Brown family in the Burnham area of Buckinghamshire, two or three in Cornwall, Hitchin is another place, and Canterbury with two or three.
But I think we need Cazza to let us know if there is anything in the context which might indicate a link. I have a ton of photos from my late m-i-l which I dare not remove from the order they arrived until I've got them all catalogued in some way. It's my only hope of giving them a definitive date. Mine are mostly people though.
Nell