It never occurred to me until
The Guardian pointed it out today that David Tennant is Campbell from Takin' Over The Asylum. And it should have done, really, because he's still doing that manic thing, but it just sounds so much better in a Scottish accent. Anyway, for those who are interested, there's a clip of him doing it embedded in that article (there's a short Co-op ad first, but about four minutes of Tennant in full flow once that's over. Ken Stott's there, of course, and as a bonus there's Angela Bruce (Bambera) as a psychiatric nurse bringing Campbell down).
I wish they'd show Takin' Over The Asylum again. Apart from all the worthy reasons the article cites, it was fun. But apparently it's coming out on DVD.
There is a logic to the icon; another character is obsessed with cleaning.