That might have happened in another book, but in Thank You, Jeeves (also great because Wooster blacks up)...
...it's a banjolele. It gets destroyed when Wooster's new 'gentleman's personal gentleman' (steady on, Tabs) gets drunk and burns down his cottage thinking that Wooster is the devil (with his black make-up on). They don't write 'em like that anymore.
( Fray Brentos www.youparklikeacunt.com, Thu 28 Jun 2012, 14:16, Reply)

It's been some time since I read the books, so I might be wrong on that,
but I am absolutely positive it's the trombone in the tv series.
www.youtube.com/watch?v=C-4r0-CrfbI&t=247
( Tusk knows where you live, Thu 28 Jun 2012, 14:41, Reply)