Conversation so far:
what radio station did Humphrey Lyttelton work for?
BBC Radio 2.
how long was he with them?
In 1972 Lyttelton was chosen to host the comedy panel game I'm Sorry.
is that all that he did there?
both radio and television.
what did he do in television?
comedic antidote to traditional BBC panel games.
Did he work for any other stations besides bbc?
CANNOTANSWER.

Question: when did he start at BBC Radio 4?
Self-contained rewrite: When did Humphrey Lyttelton start at BBC Radio 4?