I think you were collecting bilberries rather than blueberries. I could be wrong but what I wanted to say is that you just don't get them in the UK. But they make the most delicious fruit pie ever! My mother used to get them about once a year in season from an itinerant greengrocer and we would have bilberry pie for supper - utterly yummy.
I've never seen them in supermarkets or independent greengrocers, ever. I once found a bottle of preserved bilberries in a Polish grocer shop which were fine but on returning I never found them in stock again!
They do grow in the UK in remote upland heaths but to collect any you've got to travel a long way and hit a narrow ripening window just right and beat the birds! I read that they are such a delicate plant to grow that no one has ever succeeded in growing them commercially and the supplies that do come through are picked wild, mostly in eastern Europe.
So I envy your access to them, JMF! Enjoy them for me!!!
John