I have met Rowan Atkinson (in the shop I used to work for) a couple of times.
Not very funny in real life (but that is OK...)
Billy Connolly on the other hand is exactly the same as you see on TV.

True story..
One of my mates at work (originally from England) shared my sense of humour.
So in the office we used to do the Monty Python routines (he could do them verbatim I had to improvise some...) and bits from other similar UK comedy shows.
One day Billy Connolly was in the shop looking at cameras as he did when he performed in Melbourne , so my mate started to chat with him eventually sneaking in "how about an autograph ?"
Billy replied with something like "why not..."
so my mate asked "who should I make it up to ?"
Billy thought that it was funny...
No such banter with Rowan.....