Cats Protection will step in if asked, and capture them for rehoming or neutering. I have one of them here, she's a brutal yet loving cat. We had loads of them at the UKAEA Harwell site I work at, they got neutered and ear clipped. I believe someone in senior management loved cats!
Yes, and some branches will also find new homes for 'working cats.'
When the local 'wildlife' is mainly comprised of rats and mice, such feral (trapped, neutered, rehomed) cats are an effective rodent control system, and one which is both more effective and lower impact than leaving boxes of rat poison all over the place.
The main cause of little birds disappearing in UK is human activity. Not a lot of food or nesting places for them when trees are cut down and driveways paves over for car parking. Similarly the popularity of 'gardens' comprised of hard paving, furniture and the occasional potted plant. And don't get me started on fake grass.......
But easier to blame a cat than admit that human lifestyles are an issue.
TPO