Quite a few people on here have used Billy No Mates with success, but I tried it a couple of years ago and didn't notice any difference. I'm in a minority on that though

I've been told that raw fed dogs are generally less attractive to ticks than those on processed foods, something to do with sugars and other ingredients in processed foods I think. I don't see as many ticks on raw fed William and Louis as I did on my previous kibble fed Cockers, but most of their walks were in a different area of the New Forest, so that could affect the numbers too.
I'm going to be adding a mix of crushed fresh garlic, powdered ginger and brewer's yeast to their food to see if that wards off some of the ticks, but I need to check the quantities first. I was told about that yesterday at a seminar where the speaker was holistic vet Nick Thompson.