Just where in the UK do you live, Margeo? Prunus incisa oshidori should have flowered in April and be finished long ago, the leaves having started to form at the time of flowering. I assume that it must be something to do with the peculiar weather this year; cold and hot, wet and dry within days.

I live in East Kilbride where it is not uncommon for us to have snow at this time of year!! Just had a closer look at my poor cherry and find some of the leaves which have opened are covered in minute black bugs. Could this be the problem? also found a couple of small caterpillars on the branches. I have sprayed and removed most of the damaged/bare branches. Its been v. wet and cold here for weeks so maybe a break in the weather will buck things up. Thanks for responding

Don't complain to me about the weather, Margeo, I will complain back even louder ;-))). Spraying is exactly what I would have done in this situation.
Is the cherry in a pot or in the ground? If it is in a pot it could be stressed because the pot is too small or the compost needs replacing. You might want to consider a larger pot with new compost or renewing the compost in the existing pot. In the ground I am not sure what the problem could be - appart from this ...... weather.

Plant is in the ground with others which do not appear to be affected. When rain goes off I shall check again and maybe respray and cross my fingers!! Thanks for support.