The imminent general election prevented Members of Parliament running the London Marathon last year, but four of our national politicians will be on the start line in 2011, including one particular new member of the ‘most exclusive running club in the world'.

Jo Swinson is not only the MP for East Dunbartonshire, deputy leader of the Scottish Liberal Democrats, and Parliamentary Private Secretary to Vince Cable, the Secretary of State for Business, Innovation and Skills, but on 17 April the 31-year-old will become only the second woman MP to run the London Marathon.

Somehow, she found time to talk to about juggling a high pressure, high profile job with training runs and road races.

How long have you been running?
Since 2006. I entered the Race for Life with my mum and quite enjoyed it. I thought, ‘If I can do 5k, maybe I can do 10k.' So I entered a Glasgow 10k that September, and did the Great North Run that autumn. I just got the bug.

I remember finishing the Great North Run feeling very tired but not as if I was about to die or anything, so of course I had that niggle in my mind: ‘I wonder if I could do a marathon.' So I entered the Loch Ness Marathon in 2007, ran it, and swore I would never do one again. People say it's a difficult one to do, and it was really hard. The last six miles were horrible. I finished in 4 hours 7 minutes 18 seconds. Guess what I was aiming for? Four hours, of course.

My final month of training for that race was disrupted by preparing for the ‘election that never was'. I ended up ditching a lot of training and going out knocking on doors. It was actually the day before the marathon when I heard on the radio that Gordon Brown had called it off. We were driving up to Inverness and I was sticking labels on posters on the way. He wasn't exactly my favourite person right then.

But hey, if I had got under four hours I might not be doing another one now.

Why did you choose the London Marathon?
Well, it's iconic, isn't it? I would have done Glasgow but there isn't a Glasgow marathon any more, so London it was. It's such a big occasion and has all those sights en route. I used to live close to Tower Bridge when I was a student, and the finish is by Parliament and the Mall, so it all make sense ... sort of.

And why this year?
There was an event to try and get more MPs to run it in 2010. I thought, ‘There's no way I am combining it with an election'. But I said I'd think about it for 2011. You also forget about the pain after a while, and it niggled me that I didn't get under four hours. Sub-four is my aim this time.

How do you fit the training around such a demanding job?
It is difficult. I have to ‘diarise' it, so I've drawn up a training plan. I'm trying to do five times a week this time. I did three to four last time and I want to see if I can enjoy it a bit more - that's the theory anyway.

There's a gym here in Westminster I use for intervals and I tend to do my long run on a Saturday or Sunday, which is not too hard to fit around constituency work or time in London if I'm here. I sometimes start my day with a run, but we're talking 7 o'clock, not five or anything ridiculous.

Given that we work till 10pm on Mondays and Tuesdays, taking a break from the desk to go and run at the gym is fair enough, I reckon, but you have to be able to vote if the bell rings. I have, on more than one occasion, been to vote in my running gear straight from the gym. Several MPs do.

What do you like about running?
I like that I can totally relax and let my mind wander. Sometimes my mind just runs away and I can come up with good ideas, or mull over particular issues or problems. And that exhilaration you get after a really good run - there's nothing like it.

Also, it's often beautiful, especially in early morning when you've got bright sunshine. You get this part of the day which no one else has, and you experience it in a particular way, especially in west Scotland which has some beautiful areas.

It's great if you've been stressed too. The hours here are long and strained so having time to exercise makes you feel so much better. It burns off stress. Even if I'm tired I find it gives me more energy. Everything just looks better afterwards, and feels better.

The late Patsy Calton, Liberal Democrat MP for Cheadle, was the only previous woman MP to run the London Marathon. How do you feel about being the second? [Calton ran from 2001 to 2003, but died of cancer in May 2005.]

I'm very excited to be doing it, and of course it's very sad that the only other woman was Patsy. I overlapped with her briefly in Parliament after I was elected in 2005 - she died a month after the election. She'd raised money for cancer charities, and she'd beaten it once, but then it came back. So there is a twinge of sadness thinking about someone who was fit and healthy enough to run the marathon and then died shortly afterwards.

Why do you think there have been so few women MP marathoners?
Well, firstly, because there are not that many women MPs - which is something I would also like to change. Juggling the training with a job that has you in two different parts of the country, and is very all encompassing, is very tough.

And it's even harder for women who have family commitments. I expect the idea of lobbing marathon training into all that - well, you can understand why it would just be too much. I suppose some male colleagues have a more traditional division of labour within their households - that might be one of the factors.

Are you running for a charity?
Leukemia and Lymphoma Research - it's affected someone close to me. I'd like to raise a £100 a mile, so that would be £2,620. Obviously, if I raise more it would be great.

Will you have support on the day?
My fiancé [the MP for Chippenham, Duncan Hames] will be cheering me on - we get married a month later so that'll be great. My parents will come and watch too, and some of my friends in London might be persuaded.

MPs running in 2011

Stephen Crabb, Conservative MP for Preseli Pembrokeshire: London PB 5:13:41 in 2007; this is his 2nd London Marathon

Jo Swinson, Liberal Democrat MP for East Dunbartonshire: debut

Edward Timpson, Conservative MP for Crewe and Nantwich: PB 3:58:36 (2009); 2nd London Marathon

David Ward, Liberal Democrat MP for Bradford East: debut.