I think its some kind of rust- I will get in the loft and find my book about this and get back to you

tx john look forward to your answer
dave.

Hi Dave
finally got round to having a look at disease for trees and bushes. What its saying is:-
Potassium deficiency makes leaves scorch around the margins and they can be spotted, mottled or curled and may even drop off.
Potassium "potash" is a food that produces fruits, flowers and enhances the leaves/ keeps healthy. it helps with photosynthesis and the production of carbohydrates.
I hope this helps I have read the other description and I think this best describes what is going on from the pictures.
regards John

tx john for your information
dave.