This sounds a very likely explaination - especially as you say it was a big pee - he had prob been holding a while but was enjoying chilling on the bed with you

ha he hany done it since *touch wood* I thin he just forgot himself!

see my post "advice deperately needed" i have this problem with one of my cats but not just every now and again its all the time.
I change the litter all the time and he has lived in 3 different places with different people and different surrounding vut has always done it so i have no idea why he does it.
It's looking like i might have to give him away now i am so upset have been crying all day but i want whats best for him and maybe living indoors with me isn't what he needs

he he thanks for the advice..

Alfie only did this the once and hasnt done it for ages touch wood! Think he left it a bit too late before he realised he needed a wee!

Kittykatluver, has he been checked by a vet incase he has a UTI, it is so hard when they do this my cat did it about 2 years back in the end we got rid of the carpet and it stopped.
Always make sure the area is clean though as they can still smell the urine even if we cant.

These are the things that I have heard work for cat urine.
Biological washing powder.
Plain white vinegar
Spirits such as gin, vodka etc
surgical White spirit.
I have to add though that I have not used the above items apart from the washing powder, so I would just test the area first before using.

Good luck

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Mummy to 2 babies, one has 2 legs and the other has 4 xx