The real genius of Dave Allen was, unlike almost everyone else, before or since, his mastery of the silence, the long pause, the patient build up. It takes enormous self control to keep people waiting so long for the pay off. It's a tool most people who get up on stage find very difficult to use. No wonder. For a young comic the nerves and adrenalin must be racing. I know he used to love telling kids ghost stories and keeping them enthralled with suspense. I guess it was a skill developed from or in tandem with that.
Steven Wright, the american surreal one liner comic had the same laid back control, though the type of gag was very different. A number of comics could tell long jokes or stories but there were usually relatively frantic.
Stewart Lee is the only other comedian who can do this any where near as well that I can think of.