Not sure, but my favourite opening to a sketch was Ronnie B going up to a barman "A large gin please" "Tonic?" "if there's any room left in the glass!"
As well as those already mentioned, the serials within the shows were always great, the ones featuring Charlie Farley and Piggy Malone, The Worm That Turned and of course The Phantom Raspberry Blower of Old London Town ( written by Spike Milligan, and a gentleman ) ...
That one is prue quality. The other one I liked was the two of them on the phone next to each other and the two halves of their conversations meshing together to say something completely different!
Obviously the famous ones that others have mentioned are great but the 'big musical finales' they did ie 'People Don't Like Clowns No More', Somebody's Got To Do It', 'The Plumstead Ladies Male Voice Choir' and 'Barber Shop' were good too. There was also one with old Oxford graduates looking back at their younger days.
The Barker monologues were always excellent and were far better than the Corbett 'waffle in chair' spots.
Here's a sketch not seen too often featuring Barker in a 'How To' sketch about building a garden shed:
I know this is off topic and I'm sure someone's mentioned this before, but how do you post a video straight into a post rather than using a link like I did earlier? For the life of me, I can't work it out!
http://www.youtube.com/watch?v=cc3M1nppd3c
http://www.youtube.com/watch?v=5c4uMaJKt_g 
Comments
Don't know where to start. Legendary.
Specialist subject - answering the question before the one just asked.
Quality.
"A large gin please"
"Tonic?"
"if there's any room left in the glass!"
the Andre Previn - "but not necessarily in the right order"
Fork handles
and the breakfast sketch - probably my favourite.
;-P
Pisspronounciation of worms.
The Phantom Raspberry Blower of Old London Town.
youtu.be/y0C59pI_ypQ
The Barker monologues were always excellent and were far better than the Corbett 'waffle in chair' spots.
Here's a sketch not seen too often featuring Barker in a 'How To' sketch about building a garden shed:
Apologies for my stupidity.
:-)
"I'll be speaking to a lady who likes Nicholas Parsons"
"And I'll be speaking to a parson who likes knickerless ladies"
Ronnie Barker, genius!