Have just spent fifteen minutes chasing the mouse about the house in a bid to recapture it. Suspect one of the girls must have let it out of the cage to play and then completely forgotten about putting it back, and it's spent the last few hours prowling the house in search of food until it ended up in my room.

Fortunately food was a higher priority than freedom, so capturing the mouse was less aggravating than it might have been for all parties concerned.