Question Author
Greetings "rufuscat".
Thanks for your input on this.
The problem has now been sorted as I immediately returned to my earlier regime of "annointing" the little darlings EVERY month, throughout the WHOLE year. That seems to have done the trick. :-)
I did consider using more powerful stuff BUT, that would have involved each of my three cats being examined by a vet before the stuff could be legally obtained. As I now live in a rather remote rural area, I dismissed that idea on account of cost and also because of unnecessary trauma to the cats.
You might be interested to know however that I now use "Fiprospot", which contains exactly the same amount of "Fipronil" as "Frontline" does, but is a darned sight cheaper! :-)
I buy this online from www.petfleas.co.uk . You might like to check it out possibly?
Be good!
Cheers.
Mike C.