Squirrels?

Was just reading the most excellent Squirrel Power article in the Sunday Times, when I heard a rustling above and behind me. Given that we've been battling some pesky microorganisms in the house this week (more on that later) I thought, "Oh great, this is just what we need, critters in the attic."  And then I realized it was our shy but sweet cat Leon, perched in the back of Mary's photo shelves, which are behind my reading chair.