LOL sorry only just saw this!!
We bought one from Pets at Home and do you know what?! the mad cat lady took it off!! same as she's taken off all the others. I had a disk engraved saying "special diet please do not feed me" and another saying "much loved pet, send me home..." all taken off! Now I know the odd collar can slip off but this is about 11 now in a year
snowball is microchipped now so should the worst happen (as it did to her 2 sons and my persian) at least we can be told rather than always wondering if she's just at the mad cat woman's house.