The usual reverential silence that pervades most art exhibitions is curiously missing on the first floor of the City Art Centre. Instead the hush is punctuated by a series of staccato snorts and sniggers – snorts which make total sense when you have a wee look yourself. On display is a selection of cartoons from the Evening News’ daily cartoonist Frank Boyle.

“To be topical and funny and everything, it’s very hard going. It’s quite stressful you know, to do one a day and keep coming up with ideas,” he says. So, five days a week Boyle's task is to capture the mood of a story in a single frame: "a picture is worth a thousand words" is quite possibly written into his job description.

Boyle, a Glaswegian, feels his degree of seperation from the city gives him an edge: “I think it’s good to be an outsider, you know, when you see Edinburgh in a different light, as an outsider, that’s not a bad thing actually. I try to wander around, get a feel, go into pubs and cafes, and get feel for the areas. You just sort of pick up a kind of sense of what people want, what people are thinking.”

For a caricaturist some people are easier to capture than others. “Nicol Stephen [Scottish Lib Dem leader], he’s very difficult to do because he’s really not got any obvious features which kind of stick out but Salmond’s good. He’s brilliant to draw, yeah, his face, he’s got this incredibly round face. You could almost start drawing him with a compass.”

But do these politicians ever take offence at the constant ridicule? “I think most politicians have to have a thick skin because you get abused left, right and centre. But apparently some are a bit more sensitive,” pause for a cheeky laugh. “I won’t name any names but I’ve been told one or two people rather take themselves too seriously, have rather grandiose views of their own importance and they get annoyed about it.”

But it’s not all about piss-taking in the cartoon game, and there are some serious stories Boyle can simply not ignore. The exhibition features Boyle’s commemoration of 7/7, which as it came the day after London won the Olympics, he illustrated with five wreaths in the pattern of the Olympic symbol.

“You’ve got to do something. So, it’s trying to do something, a memorable image, that’ll maybe stick in people’s minds and has a certain poignancy. It’s trying to get the right balance of something hard hitting but not crass, not too sentimental.”

And that’s why Frank Boyle has become an Edinburgh institution. Because he can capture the mood of the moment, with a sharp and intelligent eye, whether with humour or sensitivity, he does it with feeling, every single day.