That's usually just a caricature though.
I'm sure we've had a fair few old buffers on the bench, but the thing about being a senior judge is that in order to get there you've seen an awful lot of court cases in your career as a barrister - and that means having to work for a whole bunch of clients and master a bunch of different briefs. This should give you a pretty varied education - if you're at all awake during it.
My experience of Crown Court judges (I've been on the jury in 3 trials with three different ones), was that they were pretty switched on and took no shit in their courtrooms.