Willow tree needs help

I think it's likely to be lack of water. The ground in pic 0009 looks bone dry, with exposed roots too. You have a lot of thirsty shrubs/ trees around it which doesn't help as it's all competition- laurel, conifers etc.
Pollarding might helps take stress of the root system, as @pete says. Less top for it to support. It would probably recover a bit over winter - assuming you're not in a dry area of the country, although you still haven't said what your climate is like. How well it would do beyond that is difficult to determine. It might be ok, but I wouldn't hold my breath.
I noticed a couple of willows in gardens yesterday when I was out, and they still had quite a bit of greenery, but it's been very, very mild so a lot of trees are still looking pretty good. One is next to a Scots pine, but we don't have a problem with water and wet ground here, so it won't be adversely affected. Willows of any kind don't like being dry for long spells.

 

Looks great @shiney. Yours certainly has more room to show itself off.
I think pollarding would be the way to go with yours @George kyriacou, just to ease the strain on those roots. It's sometimes difficult to make those decisions - especially with trees, and when you're putting it in someone else's hands, but if it's struggling to get enough moisture, it's not going to be at it's best in future.
As shiney says, this is where your location dictates timing of foliage going over, and also when it appears the following year. Only you can tell if the current situation is pretty normal, or very unusual.