This very informative article appeared in Professional Photographer - here
I always had a clause in any contract that stated the images could be used by me for exhibition, publicity etc. There is a reverse side to this problem clients seem to think because they have commissioned the work they can use it for any purpose without extra payment, I had one who wanted to print 7000 postcards of an image without payment, I settled for a prominent credit on the card which was good publicity.
Don't think that this privacy law only applies to pro's it applies to any image so street candids could raise a few problems, if someone is easily identified and the image published they could object and take legal action. It does happen more often than you may imagine. I took some shots for the local council at the town's bus station and one chap shown waiting for a bus raised hell when one of the images was used in an advert by the council, the shot was the sort of thing I could have easily taken for a personal project.