In such an atmosphere of cheerful cynicism, it must occasionally puzzle the electorate that politicians take their public utterances so seriously. After all, the excitable Member for Antrim North was only echoing what was being said in taprooms the length and breadth of the country. He asked Sir Patrick why he had issued 'falsehoods', why he had got officials to do likewise, and why those 'falsehoods' had been backed up by Downing Street.
This was too much for the Speaker, Miss Betty Boothroyd, who said that 'falsehoods mean one thing to the chair of this House - that is lies'. Mr Paisley duly obliged by using the L-word.
The spectacle was not unexpected. Twelve years ago, Mr Paisley was suspended for calling the then Northern Ireland Secretary, Humphrey Atkins, a liar. He could scarcely plead ignorance of the conventions last week. Quite the opposite: he left the chamber evidently well- satisfied with his work.
But if an MP cannot accuse a minister of fibbing, when it is patently clear that the Government has - perhaps for very good reasons - misled the people, the media and the politicians about its contacts with the IRA, is Parliament doing its job properly?
Some MPs argued privately that the Speaker may have been too quick off the mark, and could have let the term 'falsehood' through. But most opinion sided with the chair. 'You can imagine the liberties that MPs would have taken if she hadn't jumped on Paisley,' said a senior Labour source.
The rules governing unparliamentary language, though not particularly clear, are well understood. Erskine May, the parliamentary bible, charges the Speaker with maintaining 'civilised and dignified debate'. Rules allowing expulsion of MPs were introduced in the 19th century, after the disruptive tactics of Irish nationalist members regularly brought proceedings to a halt.
The Deputy Speaker, Geoffrey Lofthouse, points out that all MPs are 'honourable members' - and honourable men and women do not lie. If there is a strong feeling among MPs that one of their number has told falsehoods, he or she can be brought to book by a motion of censure. John Profumo was brought down by this device.
There are no hard and fast rules about what language may be used in the House. It is left to the Speaker's discretion. Thus Margaret Thatcher was allowed to get away with calling Neil Kinnock 'a crypto-Communist'. Winston Churchill famously coined the phrase 'terminological inexactitude' to accuse an MP of lying, while the fashionable usage since the Spycatcher case has been Sir Robert Armstrong's 'economical with the truth'.
The question of ministerial lying has long exercised the House. Robert Rhodes James, parliamentary historian and former MP, says: 'This has always been a difficult one. You may remember that in 1968 there was a classic occasion when a lie would have been right.' This was when James Callaghan was Chancellor and the question of devaluation arose. In an earlier Labour devaluation, by Stafford Cripps in 1948, the Chancellor had simply lied right up to the last minute.
'No one blamed him at all. Callaghan should have done the same. He didn't, and there was a run on the pound. Callaghan astonished the House and the Opposition by his candour.
'Devaluation accordingly took place in the worst possible circumstances.'
During the Suez crisis, ministers denied that Britain was acting in concert with Israel, though this was subsequently proved to be the case.
'The convention is that you tell the truth and nothing but the truth. But the reality is that, in government, you cannot,' said Mr Rhodes James.
There is a distinction, he argues, between not telling the truth in the national interest, and doing so out of self-interest which is 'just lying'.Reuse content