Sounds like Tomato blossom end rot have a look at the link below

http://apps.rhs.org.uk/advicesearch/Profile.aspx?PID=395

Some varieties seem more prone than others but seems to be uneven watering often linked to high temperatures......one year I got it on the third truss on evey plant

This problem was on Gardeners World this week! Not a good year 'again' for the veggies.

Great at the moment for tree fruit, never had so many cherries!

That's a plus Pam, good for you.

Blackbirds not get them? We never had any when I was a kid, as the birds were always first.

It was "attack by wood pigeon" that had us rushing out!
I don't mind the blackbirds having some, they have such a lovely song....the coo of the wood pigeon is soothing but between them and their young they would have stripped the trees in no time at all!