Last winter I used my boots a lot and noticed that they were getting some kind of white veil that I couldn't get rid off with warm soapy water.
I looked online and didn't find much apart from a quite expensive Hunter cream that they sell to take care of the boots.
I didn't order it 1. because I wanted a quicker fix an and 2. because I couldn't be bothered to pay that much.
So I kept looking and I'm not quite sure how I ended up finding that idea but I took a cloth and some cheap vegetable oil to rub my boots with.
Believe it or not, it worked wonders !
The first time, I had to put quite a few layers (letting the oil sink in for a few minutes between each layer) until they recovered their shine completely and the results started to fade after about 3 months.
Now I get my cloth and oil out about every couple of months (depending on how much I wear them) and one layer is enough to make them shine again.
(of course I wash them first with warm water and a bit of soap if needed to work on a clean canvas)
I didn't realise that Hunter boots would be quite so high maintenance but I'm glad I found a way to keep them looking like new.
Hope this trick comes in handy !