First I thought it looked like mildew but could this be Verticillium wilt ?

Possibly verticillium, they are prone to it, but usually that causes wilting first. Really need to see the whole plant rather than just this leaf - I can't even tell what colour the leaves should be and what kind of Maple it is.

I don't think you could call this a plant,it is about 14ft high and at one time had a very dense canopy. From what little I could see of the original colour it is a mixture of very pale green / light brown.

The leaf looks more like a Plane Tree than a Maple, to me....Well, with further research, it is likely to be a Norway Maple (Acer platanoides), with typical powdery mildew damage for that species.

I have looked at the Norway Maple and I would suggest you are right. I can see by the general concensus that it is a type of mildew / wilt. As I have said the tree is going to the bonfire, I would not think it will ever recover from this.This year the leaves were infected as they opened. Many Thanks for all your help I can always rely on you for sound advice

Cazoo, if its mildew, its treatable - verticillium wilts is a different, unrelated condition which would require the tree's removal.

Thats interesting Bamboo...would that be with a spray or somthing watered in???

Fungicidal spray which treats for mildew, preferably a systemic one. Bit late this year, though its probably worth a go anyway. Otherwise I'd start spraying next year in Spring as the leaves open - but of course, the tree may be too large to spray effectively.

Again many thanks for all the advice,I will certainly pass it on to my friend. I will mention the spray as well Bamboo,she may give it a go,I like to think that if we can save a tree,we should at least try anything available. Regards C

If she wants to try, all fallen leaves must be collected and disposed of, and the soil beneath the tree should be as clean and clear as possible over autumn/winter.

Okydoky