I would say your tree is dead or not worth saving. Cut it down, haul it out.

Thanks for this,I think this is probably the answer.Will give a little more time to confirm the worst Regards Dave.

It is odd that has suddenly happened ...

Did the area over winter get water logged ?
Any other shrubs close by and do they look ok ?
Have you had toadstools in your garden ?

Check the bottom of the tree and have a look at the bark ,has it been chewed away .
I had a major problem with voles and they do like to chew around the base of trees shrubs etc

So as you can see lots of reasons why it would die

A Hydrangea near by is browning upper leaves,thisbI have put down to near drought this spring?Thank you for taking the time as with other posts, this gives us both confidence to come to what seems,the inevitability of loosing this once showy,beautiful tree.No signs of any fungal type activity or voles.

If it has suffered drought and is in a windy condition I think there is very little likelihood of your Acer surviving. Watering a tree is best done a couple of times a week when you give the area a good soak and allow the water to sink into the ground if, effectively, you've been giving in a couple of watering cans full a day this won't have got anywhere near supplying the roots with water. As GG says though it does seem odd, has there been a change in that area of the garden since last year i.e. shrub/tree added or removed?

Dear Moon,thanks for your trouble.The activity around this tree has been minimal.My wife and I will give the tree a couple of weeks after which we will remove it.I have nipped a small sample of the youngest twigs and it did not inspire confidence.My thanks for your comment.