Freaked out by the fervour of her fans

Isy Suttie tells James Rampton about the joy of playing Peep Show's Dobby

Isy Suttie admits that she has been taken aback by the fervour of the reaction to her role as Dobby, the "geeks' dream girlfriend" in Peep Show, Channel 4's long-running sitcom about two eternal loser flatmates, Mark (played with uptight brilliance by David Mitchell) and Jeremy (played with louche brilliance by Robert Webb).

"I'd done stand-up and a lot of acting before, but I've never been recognised as someone off the telly," says Suttie. "But when I started playing Dobby, there was suddenly quite a dramatic change, and I was freaked out by it. I was on the South Bank in London one day, and 20 people were suddenly running towards me and screaming. They were just beside themselves with excitement at seeing me. They were shaking and shouting, 'Oh my God, it's Dobby!' I couldn't get my head around it at all."

Just what is it about this character, a woman just as happy to talk about The Lord of the Rings as lipstick, that has fans running towards her?

"Dobby seems to have struck a real chord," reflects the actress, 34, who was raised in Matlock, Derbyshire, before studying at the Guildford School of Acting. "In sitcoms, female characters are often bland. Especially if they're girlfriends – they're just there to serve a purpose.

"They will often come in with their hands on their hips, exclaim, 'What are you guys doing? Boys will be boys' and tut. Dobby is great because she is more likely to be tutted at. She is a more well-rounded character. She often takes the lead and does the crazy stuff. That's quite unusual."

Suttie identifies with the sweet-natured, eccentrically attired Dobby. "We're quite similar. Like me, Dobby is very upbeat. She doesn't want to get to the end of her life and say, 'I wish I'd done this or that.' We also both get frustrated with people who won't take risks. I think, 'Don't just sip the port – drink the whole bottle!' I suppose that's my motto for life."

The actress began her career in stand-up in 2003, specialising in silly songs. Before that, as a teenager, she was in a prog-rock band called Infinite Dreams. "We did loads of eight to 12-minute songs and projected a lot of power stations onto a screen at the back of the stage.

"After rehearsals finished, we would sit around with people from another prog-rock band – probably called Finite Dreams – and play Dungeons and Dragons. These games would go on for hours, but sadly I didn't understand the rules."

So what draws Dobby to Mark? "She admires his intelligence and the fact that he is well-read and into history and politics," says Suttie, whose real-life partner is the up-and-coming stand-up Elis James. "She also secretly likes the fact that he doesn't enjoy clubbing and will say, 'I absolutely don't want to drink real ale with that guy who doesn't know who Stalin is.' They can't stay apart. They're doomed to be together."

Suttie is now filming the final series of Shameless – "I hope I won't come back to Peep Show wanting to smoke and drink in every scene..." – another long-runner which holds a special place in viewers' hearts.

"There is a real Britishness about Peep Show," she agrees. "Even though things seem to be going well for the characters, you know something bad is just around the corner.

"It wouldn't work if Mark or Jeremy ever had girlfriends and were very, very happy with them. That's a very British approach. Our sense of humour is about laughing in the face of adversity. That's very much part of our culture. Drizzle is never too far away."