I know the CP don't advocate collars, but if people don't check for microchips as a matter of course, then a collar spells it loud and clear .... "I own somebody".
When people find a cat or think they find a cat, we always ask the finder to take to a vet to see if it is chipped or if they live near one of our fosters to them. Nowadays most rescues, all vets and some Councils have readers. I know also that more and more vets are now scanning cats as they come into the surgery to ensure the owner is the owner. The down side to me is that apart from the horrific injuries I see due to collars, a collar does not necessarily say 'I own somebody' (

I like that). So many cats that are strays come into care that have collars on and in spite of our best efforts we fail to find an owner. Sometimes we find out that the owner has moved and just left the cat or the owner has died and the family had put the cat out but of course all the other household possessions have been found a good home. I would hate for people who see a cat with a collar on to assume it has a home. If they did many cats would be strays for a long time.
my Mum has got a cat who has a thyroid problem and he is really skinny but he is so happy - Mum said today that she thinks she will put a message on his collar saying "I am loved and receiving medical attention - please don’t put me to sleep"
A year or so ago someone signed over a very thin cat over to us (we later found out that the 'finder' knew perfectly well who the owner was but that is a different story.) If another certain rescue in our area did take in strays (which they don't) the little one would most certainly have been PTS within the hour. Anyway we took the cat to the vets immediately and had full bloods, apart from the thyroid test which takes a few days for the results to come back the results were quite good for a cat of its age. Sadly a few days later the cat died. We found out it was on medication for thyroid but because some

of a neighbour thought the cat was not being cared for it did not receive its medication, who knows it may have died anyway but it just leaves that niggle in the back of your mind and of course its owner would have been able to be with the little one at the end. Had the cat been chipped rather than a collar with no identification on (it had come off) the cat would have been reunited with its owner and a letter to the 'finder' sent saying it was a much loved pet.
Anyway back to the original topic, I do hope that lessons will be learn from this and that all in the Society are informed about it and advised that they really do need to take a pet to the nearest vet immediately, then go back (unless they have another emergency) to the area it was found and make a few enquiries.