Just thought I'd pass this on.
My dog often has itchy skin, caused by grass pollen etc (according to the York Test).
Anyway, I try not to bath him unless it's really necessary and over the years I've tried all sorts of dog shampoos that are supposed to be natural - but only to discover on reading the ingredients that they are mainly full of chemicals that aren't very nice - SLS etc.
Well earlier this year I was introduced to a human hair care range - John Masters. Not cheap at all but the quality is such that you need so little that it last for ages. No nasty things in it either - I get it from a local organic haircare/bodycare shop.
I recently discovered they do a John Masters dog shampoo as well - called (wait for it !) Dogpoo !. It's so lovely - it lathered up nicely but wasn't sticky and oily at all. A lovely but very slight scent, not flowery and false. The foam just rinsed away so easily and when I dried him his coat seemed to dry really quickly - I'm guessing because there wasn't any residue stuck to the fur that all the other chemicals leave.
Anyway, just thought I'd pass it on - John Masters Organic Eucalyptus & Tea Tree Dogpoo Shampoo. You can get it online as well. It was £16 but it's going to last for ages and I think it's well worth it.

or you could try Neem shampoo from www.neemgenie.co.uk  :)

Another one that isn't cheap, but only needs a small amount because it lathers fantastically is coal tar, neem and tea tree from Hiltons Herbs.  I was given a small sample at Cruft's and couldn't wait to buy a larger bottle once I tried it.

It's great on here, being able to pick up recommendations like this.  :-)