When sitting in her office at an investment bank in the city, Kate Smurthwaite knew that converting bonds wasn’t her vocation. As an Oxford maths graduate it was a predictable and lucrative path, but not one that ultimately fulfilled her.

Kate had more to say, and she needed to say it. She wanted to discuss the world around her, particularly its political issues, and despite travelling extensively and making serious money, her voice clamoured to be heard.

Fast forward 12 years and Kate is now headlining the brand new BT comedy festival, known as a stand-up political activist whose reputation proceeds her.

Loving every minute of her change in career, Kate hasn’t regretted her decision to step away from the financial markets and launch herself as a comedian.

“I went into banking because I needed to pay off my student loans so it seemed the right thing to do at the time, but it was never supposed to be for life,” she explains.

Sneaking in to open mic comedy shows, eventually signing up for five minute slots, she slowly became addicted to her stint in the spotlight, supporting acts like Stewart Lee, before she gave up the day job.

It took her while to find her feet, before having the courage of her convictions, and talking about the things that interested her – politics, atheism, feminism, in her act “all the things I’m now known for,” she says proudly.

“But to start with you say what you think the audience wants to hear, rather than what you actually want to say, anything to get a good reaction.

“But once I started using my political voice it immediately felt right and is what I’ve used ever since.”

So what sort of politics does she discuss? “When I say political I mean talking about free speech, freedom of expression, the conflict of choice and human rights, atheism, feminism, not about Michael Gove and the colour of his shirt. My show is quite philosophical really.”

Does her niche subject matter restrict her mainstream potential? “No, not at all. There are a lot of people who want to hear my kind of comedy and they always find me. So although I wouldn’t turn down a massive show, I tend to compere because I’m not really hen night material, that’s not the stuff I enjoy doing. Generalising means limiting myself, although I like a challenge.

“I played at Reading Jongleurs to an audience made up almost entirely of the military recently,” she remembers. “They were a tough crowd and way out of my usual social range, so I went for it and lots of them came up afterwards to say how much they had enjoyed it. But then I do like to get up there and milk a show it for all its worth,” she smiles.

It’s obviously working. Now on her 12th solo show and en route to Edinburgh when we speak, Kate says: “I’m not alone. There are lots of political comedians – Marcus Brigstocke, Mark Steel, Mark Thomas.” Not many women though?

“No, comedy does tend to be quite laddy in general and attracts crowds that expect that. It’s self-perpetuating. So it’s great to find clubs offering an alternative, like the BT.

“I can’t wait to come back to Oxford because I performed there as a student and love the fact that this is an offbeat comedy festival, and much more intimate, which is where I feel most comfortable.”

But surely if she dabbled in theatre at Oxford, her comedic roots grew then?

“Not really, I did a bit of theatre when I was a student but I always played the housemaid, so a career on stage wasn’t really an option,” she says.

“And yet when I eventually gave comedy a go, I got a real buzz out of it. I like things like bungee jumping, I’m a bit of an adrenaline junkie, so it was great when it came off.

“Because although my work might be very specific, it’s also very funny and my audiences know what they want and what to expect. I don’t need billboards to tell people about that.”