Thanks again for the replies.
If we had an edit button I would show you the photos briefly, but I'm not having them on here as well 
There really is nothing that identifies me. One is a wall of bespoke bookcases, and there are photos of walls in three rooms with closeups of the old colour next to them. The only visible furniture in those ones is covered in dust sheets. As Oreo said, anyone who's been to the house will recognise it, as you can see fireplaces etc, but as has also been said, in that case they are friends anyway, so it doesn't matter.
It is the principle, really. I am a private person, and it just doesn't sit right. I want the carpenter to come back and do some additional things that are on top of the original brief, so I think I'll wait until that's done and then say something, or maybe take a photo of my own and offer that 'in case he wants to use it, as I didn't give him any whilst he was here'. I'm not sure if that's passive aggressive or diplomatic, but I'm not sure I care 
I think it's been thoughtless, rather than underhand, in all cases; but I do think that good practice would be to ask before taking photos in someone else's house in any circumstances.