It was a very English art form that Frank Johnson practised. A good parliamentary sketch can be high art, but art with a hard-nosed purpose. Sketch writers know they are an important arm of the democratic process. Unless we can laugh at our politicians we can never keep them in order.

Johnson was one of a handful of writers who helped to bring about a minor journalistic revolution in the 1960s and 1970s. Until about that time the cheeky chappies of Fleet Street were to be found more on the political left than the right. Johnson had the luck to emerge as a sketch writer when Conservatives were looking for a bit more fun in what they read about politics in their newspapers. It was a bit like what happened when the Salvation Army sent its bandsmen into the street because it felt that the Devil ought not to be allowed to have all the best tunes.

That other Johnson, the Great Doctor in the 18th century, famously said that he “took care that the Whig dogs should not have the best of it” when he reported parliamentary debates in the Gentleman’s Magazine. In the case of his 20th-century namesake, for Whigs, read Harold Wilson and his colleagues in the 1970s — or woolly liberals of all parties. Frank Johnson was good at poking fun at politicians right across the spectrum.

When, as sketch-writer of The Times, he was named Columnist of the Year in 1981 the judges described his sketches as “a daily delight — irreverent, immensely readable and always entertaining”. But it was more than entertainment. He did as much as the more “serious” commentators to raise awareness of the forces that were changing the political landscape.

He could pack a very great deal in to a single paragraph, as on the occasion of Michael Heseltine’s front bench début after Margaret Thatcher promoted him from the Department of the Environment to Defence. The date was 1983. Thatcher was riding high after the Falklands conflict and, because the campaign had accustomed the House to hearing much of the doings of the Royal Navy on stormy seas, Johnson chose suitably nautical imagery:

“The Government’s controversial new Heseltine went on its first sea trials. Scores of Conservative backbenchers lined the shore. All of them were conscious that Mr Heseltine might never see a home ministry again. Many of them were worried that he might.”

Johnson (always reluctant to pack in useless adjectives) preferred simple sentences, but in that one paragraph he was conjuring up the atmosphere of the Westminster village of the 1980s: a Tory party deeply suspicious and frightened of an ambitious, non-Thatcherite who could pack the House; an uneasy party that sensed how much trouble could lie ahead for any Cabinet containing both Thatcher and Heseltine.

Johnson had little empathy with Heseltine’s centrist kind of Conservatism — nor with Labour’s centrist rebels when they hived off, during the same period, to form the Social Democratic Party.

On Shirley Williams, he wrote: “Mrs Shirley Williams, who is regarded by some of the more primitive followers of the SDP as possessing divine status and miraculous powers, unsuccessfully applied to the Speaker for an emergency debate on the water dispute. At first, one assumed this was because the dispute was beginning to threaten supplies of the only water used by the SDP: Perrier water.”

Satirists have always aimed their fire at the Establishment, and in Thatcherite eyes the Heseltines and Williamses represented a new Establishment, resisting the forces of progress. “Wets” were fair game. An important part of Mrs Thatcher’s constituency was “Essex man” — people whose instincts were more working class than middle-class, but who had seen through the pretensions of former working-class heroes — socialist ranters and trade union officials who laid down the rules of how the workers should earn their money.

As a parliamentary reporter and later as an editor — he was Editor of The Spectator from 1995 to 1999 — Frank Johnson helped to foster that process of political evolution. In this, his own background was important. His Who’s Who entry described him as the son of a pastry cook and confectioner: perhaps he was trying to tell us something. His formal education had been minimal — despite which (or perhaps for that very reason) he was a highly civilised journalist.

Brought up in northeast London, he failed his 11-plus exam and went to a secondary modern school, a school which as it happened, had something special to offer him. It had an understanding with the Royal Opera House to send along boys to fill minor roles in productions involving crowd scenes where a few likely lads looked good on stage.

Johnson liked to recall how in one of those roles he was clutched to the bosom of the great Maria Callas (as her son) for long dramatic moments in Bellini’s Norma.