His job is a bit like working as artist-in-residence at the chamber of horrors. For more than 40 years, Gerald Scarfe has produced images of grotesquely unpleasant people. Carping, hectoring bullies. Dishonest, on-the-make chancers. We call them politicians; he calls them monsters.

With the licence that comes with a cartoonist’s set of inks, he manages to lump them all together – murderers and torturers such as Robert Mugabe and Idi Amin occupy the same space as those who might register as only mildly unpleasant on the political Richter scale, such as David Davis and Michael Howard.

Exaggeration is not so much the prerogative of a cartoonist but a prerequisite. Scarfe himself comes across as a chaise-longue anarchist – by nature a gentle soul, stirred and made livid every day by the lies and chicanery of our political masters. “I suppose I am left of centre, certainly on the liberal left. But I regard most politicians as unspeakable, lying, fundamentally dishonest, lining their own pockets and hoodwinking the public. They are all, to a varying degree, monsters of a sort. Even mild-mannered John Major was monstrously inept as a prime minister.”

When Scarfe started work as a political cartoonist, with no internet, his only reference material was black-and-white photographs from newspaper libraries and the warm glow of a television tube. In those days he would spend time on the road, attending the party conferences, staking out his prey in its natural habitat. “It helped to see someone in the flesh – it often revealed something that you could not get from a photograph. I’d no idea Denis Healey had such an incredibly red face until I met him.”

Occasionally these observational forays – think the gorilla house at London Zoo – would result in face-to-face encounters, but in principle Scarfe prefers to keep the politicians at arm’s length. “I don’t mix with them and I don’t particularly want to meet them. I might like them, which would not be good for my work.” One politician to whom Scarfe took a particular dislike was Edward Heath, whom he met at a lunch given by a newspaper editor. “I couldn’t keep up with all the intricacies of backbench politics that they were talking about, so I didn’t say much. But Heath said something like, ‘What the bloody hell is he doing here?’ as if I was superfluous. He was incredibly snotty, and I remembered that whenever I drew him.”

Scarfe was equally charmed by Heath’s contemporary Richard Nixon. Sent by Time magazine to cover the US presidential election in 1968, Scarfe found himself on the Republicans’ press bus. Nixon had tried to get him thrown off, but in those days Time had huge clout and Scarfe’s editor simply ignored the command. The cartoonist remained, and every morning Nixon would come over and say the same thing: “I hope your pencil is sharp, Gerry.”

“He was a real creep, sweaty and dishonest.”

Scarfe also met Tony Blair, who dropped in for dinner at a mutual friend’s house. “He was a newspaper editor and he’d helped Blair when he was on the way up. Somebody said that my cartoons were savage, but the charming Tony said he didn’t think so at all.” He might have changed his mind if he saw Scarfe’s drawing of him with blood on his hands after we went into Iraq.

Scarfe comments that if politicians dislike his work, they rarely have the courage to say so.

“It makes them look as though they can’t play the game. Even if they are seething, they have to look like they are good sports.” He once had lunch in the same restaurant as Norman Lamont, “who was extremely civil. Strange, as in my drawings I’d always metaphorically tipped duck soup over his head”.

Ultimately, he says, the true monsters become so thick-skinned that they see any cartoon image – however grotesque – as a hallmark of their success. “They see it all as good publicity, however I draw them, which is infuriating. David Davis had a chuckle for the cameras and said thanks very much; John Major was very civil.” One wonders whether Robert Mugabe would be quite so forgiving.

Monsters: How George Bush Saved the World – and Other Tall Stories, by Gerald Scarfe (published on Thursday by Little, Brown, £40), is available at the BooksFirst price of £36, including p&p. Tel: 0870 165 8585. Hung, Drawn and Slaughtered: Five Decades of Political Caricatures is at Portcullis House, London, from September 20 to November 27. Visit www.parliament.uk/exhibitions and www.geraldscarfe.com

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