As the leader in question was Margaret Thatcher, she did not find them funny. He was famously described by her press secretary, Sir (as he then wasn't) Bernard Ingham, as a "semi-detached" member of the government. Mr Biffen responded by calling Sir Bernard the sewer rather than the sewage.
By this time he had been removed from Mrs Thatcher's cabinet and was about to embark on the last phase of his career, as the most highly regarded backbencher in the House. His only rival was a Cambridge contemporary, Tam Dalyell, who in those undergraduate days had been a Conservative. Mr Biffen has been one all along.
But he has been his own sort of Conservative. When we talked in his constituency, before and after his speech at the new candidate's adoption meeting, he said he disliked being called a "maverick". He was merely independent. He thought the Conservatives would probably lose on historical grounds, because they had been in for 18 years. But he did not think this the worst government ever, not by any means.
He started off as an admirer of Enoch Powell, though of his views on economics rather than on race. He also had a certain regard for Edward Heath "because of his efficiency". But "as Mrs Thatcher might have said, he withdrew his love".
When Mr (later Sir Edward) Heath fell in 1975, Mr Biffen voted on the first ballot for the late Hugh Fraser, who was standing as an exponent of "traditional Conservatism", and on the second not for Margaret Thatcher but for William Whitelaw. "I happen to think Willie would have been a very good leader."
Mrs Thatcher, however, did not hold this against him. In opposition in 1974-79 he was talked of as a future Chancellor of the Exchequer. This alarmed Mr Biffen. As he said about MPs generally: "We're not all overwhelmingly desirous of being ministers."
But he accepted the job of shadow spokesman on trade, found it too much of a strain and gave it up. This led Sir Peregrine Worsthorne to write an article lamenting the folly of awarding senior positions in the Tory Party to the products of grammar schools. Mr Biffen had been to one in Somerset, where his father was a small farmer. Sir Peter Tapsell went around saying: "No, I don't think I'll do that. I'm feeling a bit Biffenish today."
Mr Biffen had always suffered from depression - from black moods, of which his resignation from the opposition front bench was the latest manifestation. On the whole, he had learnt to live with them. But now he discovered they could be treated medically. He still takes Lithium.
Mrs Thatcher could not have been more sympathetic. He pays tribute to her personal kindness and her consideration for the Prime Minister's domestic staff. "They got a better deal than the Governor of the Bank of England."
Yet he was never completely at ease with her. This was not really surprising. She was an enthusiast: he is a sceptic. Moreover, he has "never been happy about adversarial politics". In Mrs Thatcher's last phase, 1987-90, he thought "the thing"- that is, Thatcherism - "had run away with itself". He was particularly opposed to the poll tax.
So in the first round of the fatal ballot of November 1990 he voted for Michael Heseltine. "I had to pick the lock by voting for Heseltine." In the second round he voted not for Mr Heseltine or John Major but for Douglas Hurd. "I was the last of the deferentials." In fact Mr Hurd had been another Cambridge contemporary.
Since 1990 Mr Major has seen him only once. That was to rebuke him for writing an article in a Sunday newspaper calling for a reshuffle. Still, Mr Biffen thinks he has done a reasonably good job, except over Europe, but that no one at all could have done a good job over Europe with the party in its present mood. He also thinks "the Tories would be very unwise to go for an early decision" on Mr Major's successor. It is, however, unlikely to be Michael Portillo, who has "made his run too soon".
Mr Biffen's earliest hero, Mr Powell, once said that all political careers ended in failure. Mr Biffen does not repine. Leader of the House was about right for him, he believes. "Dear old Oswestry," he said as he drove me back to my hotel. He is glad to be retiring there, though he and his wife are keeping on a small flat in London because "Sarah is more a London person than I am".