As the recent scandal over the cartoons of the prophet Mohamed published in the Danish paper Jyllands-Posten has shown, visual satire still has the power to shock and provoke us. Visual satirists have always held the enviable position of being able to challenge the status quo, using comedy as their weapon and their defence. Such artists regularly manage to evade the strong arm of the law by telling their victims to lighten up, whilst flirting with the kind of defamation that could bankrupt their editors. More importantly they have long been under-sung as chroniclers of British society, overshadowed by authors, artists, and historians, yet offering a unique street level perspective of public opinion over the last 300 years.

The decision to rectify this injustice has been made by the Museum of London, who pay tribute to the art of visual satire in a new exhibition, 'Satirical London: 300 years of irreverent images'. London has always offered rich pickings for the visual satirist, being the beating heart of British politics, professions, and people, a melting pot of every risible theme and individual a society has to offer. The exhibition charts the changing techniques in these artists, and the inimitable way they have captured the less seemly side of us urbanites, focussing on the kinds of vice, folly, and unsociable behaviour that teem with life in the Capital.

The origins of visual satire in London can be traced back to the 17th century when popular prints were produced, using crude symbolism and folk imagery, by amateurs and professionals alike. Famous artists included William Hoggarth, Hollar and Rowlandson, and work of the day usually involved accurate representations of one's targets, and a heavy reliance on accompanying text.

However in the 18th century the straight drawing styles of these artists began to be replaced by caricature, an Italian tradition brought to London by travellers on the Great Tour. Their skill of distorting faces to comical effect, (a technique actually hated and satirised by Hoggarth himself) was incorporated by English artists, and the need for explanatory text was usurped by physiognomy, the art of exposing character traits by exaggerating someone's physical features in a drawing, particularly those of the face and head.

Despite Hoggarth's rejection of the new school, the skills of satirical artists were highly regarded by artistic luminaries such as Degas, Manet and Whistler who ironically described Punch Cartoonist Charles Keene as "the greatest English artist since Hoggarth".

The popularity of caricature flourished in the 18th century with the burgeoning of Print shops which served as free exhibitions for the public, and showcased artists such as James Gillray and his epochal work 'Very Slippy Weather' (1808), which found its fame through one Mrs Humphery's Print shop, based in St.James street W1. The great attraction of such prints was their relative cheapness, which allowed all classes access to their ownership. Prints however soon took a second place to magazines and journals that became, by the 1840s, the main outlet for satirical art. Amongst the first of a plethora of popular titles was the long running Punch, established in 1841. Artist John Leech whose work includes the Harmonious Owls 1842, wisely depicting men as owls, actually christened the word 'cartoon' in describing Punch's artwork.

Perhaps the most revealing aspect of the exhibition is the way visual satire in London right from the time of Hoggarth effectively managed to expose and challenge major contemporary issues, acting as barometer for public opinion. With the Industrial revolution in full effect, London was a hotbed of political activity and class struggle and satire kept its finger firmly on the pulse of this rapidly changing city, leaving us with its unique historical perspective. The professional worlds of Law, Politics and the City were targeted, striking examples being 'Another Slice of plumb pudding for Councillor Wallop' (1774) by I. Sedge, which depicts a swine-like city worker being fed by minions. Satirists used public parks, areas where all the classes rubbed shoulders, as backdrops for cutting exposes of London's social make up, and its have and have not culture. The poor were mocked as well as defended and it was not uncommon for satirists to court prejudice, as well as to attack it. Lewdness was also used as comic fuel in works like 'A high wind in St.Paul's churchyard' by S.W. Fores which illustrates a gust of wind blowing a woman's dress up while a passer by ogles her rear end.

Moreover, satirists managed to capture the ups and downs of city life seen with works by Isaac Robert Cruikshank showing pickpockets at work near St James's Palace, and Pierce Egan's 'Life in London' serving as a comic tour of London's street life. Perhaps the most famous print attacking vice is Hoggarth's Gin Lane (1754), which details debauched city dwellers succumbing to the demon drink, and was masterfully parodied by Martin Rowson in 2001, with his contemporary take, 'Cocaine Lane'.

While as a popular art form visual satire has not dominated the 20th century as it once did, modern artists like Rowson, Steve Bell and Gerald Scarfe have ensured it remains a an all pervading force. Programmes like Spitting Image (first shown 1984), some of whose puppets are exhibited here, have also proved extremely successful. Just looking at the grotesque puppet of Margaret Thatcher, provocatively dressed as a 'Sex' era Madonna, shows how precariously visual satire can tread the line between cruelty and humour. While journalists seem to be in court daily paying through the nose for misquotes and other libellous comments, visual satirists seem to have been granted a carte blanche for what they can, and if it even applies, cannot say. Long reviled by their victims, they are notoriously hard to prosecute as a number of high profile cases have shown. When Samuel Ireland attempted to sue Mrs Humphrey for exhibiting a Gillray print of him at her shop, the case was dropped after advice from his legal counsel. Another satirist let off the hook was Ian Hislop, editor of Private Eye, who managed to achieve public vindication in high profile cases against Robert Maxwell and Sonia Sutcliffe, the wife of the Yorkshire Ripper.

So while the battle concerning events in Denmark wears on, with Muslim groups seeking damages from Jyllands-Posten, and the paper's editor in chief in turn suing their lawyers for defamation, the actions of the artists involved have divided the world. Whether they are ambassadors of prejudice or of free speech is yet to be seen, but what is clear is that that artists like them have been pushing the boundaries of public opinion for centuries. While their rough and ready work may never attract the praise given to the other arts, one look around the Museum of London's exhibition shows that only a fool would doubt the power of the cartoon.

'Satirical London' is at the Museum of London (0870 444 3851) until September 3rd.