We've got piles of cats around our holding, none of them are feral as far as I know, but there's at least 6 or 7 that hunt on our land. If nothing else, it saves us getting a barn/farm cat for our own needs, but I do worry about the local bird life.
I'm slightly surprised at the catch-neuter-release policy mentioned previously. Certainly the neuter part is to be applauded, but I would imagine there is a serious conservation argument for getting these cats out of the countryside. I imagine the RSPB wouldn't approve of the re-release.
You then do end up in some sort of imaginary year-zero sort of argument.... "wild cats used to be common in britain"... well, yes, but so were Rhino. It's at that point I realise that I'm not a true conservationist, as I have no idea which era we're trying to replicate.
I find the simplest fact relating to this is that song birds numbers have decreased hugely in the last 50/60 years, and cats are one of the big culprits. With that in mind, it does seem odd that an animal charity would re-release them.