Johnny Speight was the 'writer' for loads of variety shows in those days, could be for a couple of lines or whatever - just like Colin or Adam Bostock-Smith is today you will find their names even turning up on game shows like The Weakest Link, they might have written two words for Anne in the whole show?
These type of writers just oiled the works, while comedy writers (like Barry Cryer)were brought into write the gags.
Deal or Deal has dispensed with all that old style studio system and is probably why it can afford higher prizes?