Thanks Jim. I've always thought virus but couldn't match it with anything. I think it's got to go, it's not really nice to look at any more, although may be because I know it's sick I wanted it out years ago but OH thought it might get cured
Thanks flowering rose, It's not sterile, or it wasn't, it's more or less stopped flowering now. There probably is competition for moisture etc now.
The trees were all bought together as Prunus cerasus. They're all different though. The one on the right has large cherries, black and sweet if the pigeons let them develop. The sick one was OK in fruit but not as good. The one on the left, not so sweet but still large. They are close together. 20years ago I didn't know how big a wild cherry grew. We can afford to lose one
It may remain a mystery.
No more tree surgery til next winter now though. I've had more than enough of shredding.