City Blues: Cartoons by Marf, Guildhall Art Gallery, London

If the 2008 banking crisis had an architectural motif, it was the Gherkin. In City Blues, a series of cartoons about the financial crisis by the female cartoonist Marf at Guildhall Art Gallery, it appears at least a dozen times, an instantly recognisable shorthand symbol for the Square Mile's decade of excess, self-celebration and collapse. In one cartoon, the Gherkin has even found its way into a lap-dancing club, having morphed into a decorative penis. Its familiar form presumably offers a reassuring sight for the attendant bankers who, the caption tells us, are strictly forbidden from enjoying any sort of "quantitative easing".

Marf is Martha Richler, a Canadian-born London-based political cartoonist who found herself drawing increasingly about the banking crisis and is now publishing a book on the subject. It's interesting to compare her loose, thick-lined, dramatic style with the best-known Square Mile cartoonists, Peattie and Taylor, who write the neat and precise Alex for The Daily Telegraph. Marf's cartoons are populated by a similar parade of familiar characters, but have a blunter approach – both in terms of appearance and humour – than the occasionally coy and cosy City insider Alex.

Marf's treatment of the bankers themselves lurches from savagely condemnatory to meekly pitying, reflecting perhaps public opinion at the different times at which they were drawn. At times, the bankers are corrupt and selfish leeches of public money, arrogantly oblivious to the mess they have created or positively revelling in the financial opportunities the crisis has created. "Incidentally James, how's the recession going?" asks one from the bank of his chauffeur-driven car as he drives through dramatically destitute London streets. In another, two bankers' wives marvel at the bargains on offer in the shops, as retailers frantically slash prices to attract custom: "I must say, this recession is growing on me," they giggle from beneath mounds of bulging shopping bags.

Elsewhere, however, the bankers are treated as victims, potential suicides, apologetic patsies and unfair targets of public hate. In one of her best images, City-workers are portrayed as helpless extras from The Scream, faces drawn in Munchean terror as they examine the plunging FTSE. This time it is the secretary who is oblivious to events, sitting at her desk amid a sea of depressed visages, nonchalantly filing her nails.

These more sympathetic approaches may have been what convinced the City of London Corporation to hold this exhibition at the Guildhall Art Gallery, the City's rather formal gallery located bang in the middle of the Square Mile. The gallery has recently allowed free entry and been rehung throughout, a process that has seen the creation of this new exhibition space in the undercroft. The hope is that City workers will stroll along in their lunchtime, have a gander at how their profession has been regarded in recent years, and then, print in hand, wander back to their offices, safe and snug in the shadow of the all-seeing Gherkin.

To 20 June (020 7332 3700)