General question from a discussion how do u prove owneership of a cat ? Would it be the person who could prove they bought the cat ? Would the microchip prove ownership or is it not possible to prove ownership ? Is it different with dogs ?

Micro chip would be I would have thought

Same thing as with dogs. Microchip or registration doesn't really prove anything as they frequently are not kept up to date but can help as extra evidence in a dispute. Receipt of sale will also help if available, but otherwise who is feeding, has the cat registered with the vet etc -the more pieces of info there are in the name of the owner, the better. There have been cases where people have let cats out and two different persons claim ownership and then things like photographs of the cat in the home have been taken into account as well.

If you read  the Petlog website,  microchip only  proves "keepership"    which is not the same as ownership.    In the same way as DVLA will refer to the keeper of the car,  as do the police if you get a speeding ticket.

I would think having a receipt  for the purchase of the cat,   and receipts for vets bills,  food bills,   vaccinations etc would be  counted as proof?   Photographic evidence of the cat with family members in the house over a number of  years?    In other words cumulative evidence.

ETA   -   Tattoos and their paperwork count as proof of ownership,  as the animal is treated in law as a possession,   and in this case  you have marked your  possession with a permanent identifying  mark registered to  yourself as  the owner.

thank you all very helpful