In the road I live on, there are 2 trees and in the 30 years I've lived here I've never found out what they are. They never both blossom the same year, they take in it turn and the blossom is a lovely pink. Then comes the nuisance part, fruit appears that the neighbourhood kids spend the next couple of months throwing at cars, each other or just squashing underfoot. It looks like apples, very dark red, squishy and although kids do bite into them, they soon chuck it down because it's inedible. The road is littered with the things at the moment. Not medlars, not crab apples, what else could they be?
Could be either of one of the many species of Prunus or Malus families. These are generic plum and apple families respectively, but have been developed for their blossom not their fruit.
Thank you. I've just looked at Prunus and I think they could well be that. As you say, there are loads and when I have time (ie. not at work!) I'll have a good look through.