Christie Davies recalls the bulldog spirit of caricaturing

Churchill was short - 5ft 7in - yet cartoonists always made him look much bigger than he was. Only in failure did he shrink. After his electoral defeat in July 1945, Vicky in the News Chronicle showed a large, confident Churchill striding forward, and, following in his wake, a small, humble Clement Attlee carrying two suitcases labelled "Potsdam". In the second frame, however, a small, dejected bag-carrying Churchill tags behind a jaunty Attlee.

Churchill is best remembered as the great war leader, an inspiration to the country, when for a long time Britain stood alone against Nazi Germany. Cartoons of him in this role are memorable, both as an influential part of our history and as examples of cartooning at its best.

David Low drew him in this heroic mode, notably in All behind You Winston (May 1940) where Churchill and politicians of all parties stride forward, coats off, rolling up their sleeves for the fight against Hitler. In Britain's Greatest War Leader (May 1945), Low has the ghosts of the pointy-nosed Pitt the Younger and the floppy-haired David Lloyd George help Churchill onto the plinth that rightly awaits him.

The exhibition is balanced, though, with Churchill's failures also emphasised. As Chancellor of the Exchequer, he was, John Maynard Keynes claimed, the architect of British economic failure in the 1920s. His indifference to the ordinary taxpayer in the 19 budget angered the cartoonist Strube of the Daily Express . Strube's famous "Little Man" is shown poking a large Churchill in the ribs, saying "I want a word with you, Churchill. Come outside!" The Chancellor is then shrunk frame by frame until he is so small that he stands on the palm of Little Man's hand - to be blown tumbling through the air with the admonishment: "Now get back to your work!"

Pravda saw Churchill as the great Cold War-monger, and the exhibition includes a hostile cartoon of Churchill and Ernest Bevin by Efimov, Stalin's favourite cartoonist.

The saddest and most cruel portrayal is by Illingworth, in Punch of February 1954. It shows Churchill at his desk in a dark room with his papers and dispatch boxes. His spectacles lie next to an ashtray with a dead cigar. Churchill's empty, crumpled face looks into the distance. The inscription, after Psalm 104, reads: "Man goeth forth unto his work and to his labour until the evening."

Churchill clung to office until, at 79, he was too old and sick for the post's demands. Yet only the jester Illingworth in Punch could tell the full truth. The cartoon angered Churchill, but he relinquished office a year later.

It is fitting that the exhibition - on the 40th anniversary of Churchill's death and 60 years after the end of the Second World War - is to be opened by Churchill's daughter, Mary Soames, and that Tim Benson's accompanying book has a foreword by Churchill's last surviving minister, the otherwise long-forgotten Sir Edward Heath.

There is enough here to make this exhibition of the biggest drawers of Churchill one of the biggest draws in London.

Christie Davies is the author of The Mirth of Nations and The Strange Death of Moral Britain , both £28.50 and published by Transaction.