Hi, I'm new to the forum and am looking for a bit of advice.

Six months ago two lovely black and white moggies (brothers) turned up on my doorstep begging for food and shelter. It turns out they had lived in a house over the back from us and the owners had moved out leaving the cats behind. One cat was left outside the house and one inside the house and it was over a week later that the cat was discovered inside the house and booted out to join it's brother on the streets. Needless to say, by the time they got to us, one of them was extremely skinny and his backlegs all buckled because he hadn't been able to eat for so long.

Anyway, we decided to keep them and named them Charlie and Croker (after Michael Caine's character in the Italian Job!). Charlie is the one who was starving, but he is now fit and healthy. The vet said they were about seven or eight months old at the time and they are now coming up to their first birthday.

The problem is that Charlie keeps having little accidents on the living room carpet. They aren't frequent at all. He peed last night on the carpet, but hasn't done it for six weeks before that. It seems that everytime I get confident in him, he goes and shatters it for me. I now have to watch him like a hawk when he's in the living room and he probably won't do it again for weeks, but then just when I feel like I can trust him, he will do it.

Does anybody have any idea why he is doing this? They are outdoors cats and they generally go to the toilet outside, but I do have a litter tray in the house for them for overnight and they both do use it. I clean it very regularly so there is no reason why he shouldn't want to use it.

Croker never has this same problem.

Charlie is also difficult to train in other areas, i.e. they are not allowed on the window ledge in the living room as they are destroying the blinds. Every time they go up there they get put back down and told 'no'. Croker has got to grips with this and doesn't bother trying anymore, but Charlie just keeps on doing it. Every time I pick him up and put him back down, he just jumps back up. After advice from somebody at work I even tried the water pistol method, but he still doesn't seem to understand that he isn't allowed up there.

Anyway, I've gone on a bit, so I'll shut up now and hope that somebody has any thoughts on why Charlie is being a naughty moggie!

Thanks