Frontline Spot-On for Cats. 6 pack free P+P for new customers or spend over £29 else add £2.49
If you have a cat/dog you will know fleas are a problem this time of year.
I've tried Bob Martin spot on and it doesn't work, Frontline works. This is the best you can get without visiting the vet.
This is the cheapest I could find. Hope this helps others.