This sounds like allergies. Does he also chew/lick his paws? That's another cardinal sign. Do you have Vet Dermatologists in the UK? Bc that'd be the very best thing you could do for him - the Vet Derms really deal expertly with allergies.
Here in the US, the things we use for allergies are over-the-counter Anti-histamines, fish oil (put on their food), and then the prescription items are -- Atopica, Temaril-P, steroids.
What food is he eating? Did you change the food before the symptoms started? How long has he been itchy like this...and does it come and go with the seasons?
Also, read this:
http://www.yorkietalk.com/forums/die...tart-here.html