By 6:45 this morning one cat had brought in a mouse (his first in doors) - thankfully he was growling this alerted me to what he was up to - I'm afraid I ran him before he put it down for a quick play.  After that Oscar decided that nothing would do her but have a whizz in the box they'd all been playing in.  If I could have I'd have gotten rid of them all there and then.  
So that was a quick lesson in how to make a grumpy person very grumpy - we've also run out of cornflakes!