Nope, the Advocate was used a couple of weeks ago in case it was fleas but has made no difference. The condition developed last year over a long period.
Today I am bringing a sample to the vets to go off to the lab. I gave the leison a good scraping with a clean tootbrush this morning which he enjoyed immensly
and purred away.
It could be fungal in that where I live it now rains most days of the year and we only had four dry days this summer, and he is an outdoors cat who sleeps in a straw bed in a shed.
I think if it was ringworm it would possibly have spread to me and the other cats a long time ago and would have spread to different areas of his body. As two vets have failed to diagnose and none of the Purrs so far posting have experienced it on their Mogs it maybe something unusual but we shall see.
Glad of suggestions and will certainly keep you informed of the outcome.