“Not only that I've spent in the region of £4000 getting in specialists to make the garden cat proof, the cats just sat there watching and working out how to bypass the system and they decided to climb the brickwork, so we then decided to use smooth plastic and they still managed it..... ”
£4k making the garden cat proof! Be cheaper to build them their own extension 
I actually watched the BBC Cat Watch on iplayer last night and it was pretty interesting. If anyone remembers, it built on the experiment done last year where they fitted collars to loads of cats and plotted where they went.
This time they are doing the same again, but comparing farm and country cats to town and inner city cats. With farm cats being nocturnal and house cats following their owners routine, although they are better suited to being nocturnal.
Didn't realise they had whiskers on the bottom of their legs, and combined with the mouth and eyelash whiskers, these are all basically parking sensors which is what makes them so agile, plus in very close range, they are pretty much blind as bats and rely on whiskers to track prey.
Mind you, like Clive, would appreciate if any prey was left outside and not set free in the lounge!