Lembit Opik can’t help but provoke interest. If it isn’t asteroids colliding with the planet, it’s his very public relationships, most recently with a certain Transylvanian pop star. But what about his day-job? The mild-mannered maverick, 42, got his first taste of politics when he was elected President of the University of Bristol students’ union. He also went on to win a seat on the National Union of Students’ National Executive Committee. So was this a conscious master-plan to get into national politics – when did Opik decide he wanted to be a professional politician? “I don’t think I have yet”, he contends. “I don’t think that I regard myself as a politician – more of somebody in the business of making a difference. If I could make the changes to society that I want to see without being a politician, then I would.”

Here is a man who, besides all the froth of his television appearances, is genuinely interested in working for social change. He cites his central achievements at the head of the students’ union as organising the student bus service (a service which controversially ceased last October), anti-apartheid campaigns to try to get the university to disinvest from South African businesses, and campaigning against student loans. “So things haven’t changed much in two decades.” Indeed, Opik hopes to be standing for another presidency – this time for the Liberal Democrats, when Simon Hughes steps down next year.

Opik asserts that students have never had it so bad. “Financially, the deal is a lot worse than it was in the 1980s; partly because many of the student politicians who I marched shoulder to shoulder with against a Conservative government that was going to introduce student loans, became Labour MPs who voted for top-up fees when the Labour Party came in. I think also there’s more pressure to do a vocational degree than there was in my day.” Opik began his Bristol life studying Aeronautical Engineering, before switching to Economics, and finally graduating with a Philosophy degree.

The MP’s relationships, first with TV weathergirl Sian Lloyd, and now with Cheeky Girl, Gabriela Irimia, have been very publicly documented. It begs the question; was Opik a bit of a ladies’ man in his student days? “I’m not even a ladies’ man now”, he laughs. “It’s flattering to have so much attention on my private life, but the British public are smart enough to see the difference between who you’re going out with and what you’re trying to change. Actually, she’s very popular in my constituency.”

It is clear that the surreal private life of the endearing MP for Montgomeryshire, and Liberal Democrat spokesman on Northern Ireland and Wales, has earned him a place in the popular imagination. But Mr Opik is clear about what he would want to be known for if he had his way. “One of my main campaigns is to find a cure for motor neurone disease. My father died from it two years ago and I am working with the Motor Neurone Disease Association to find a cure. My judgement is that this is where we really can make a difference. Also, I’ve been working in the peace process in Northern Ireland. And of course, my views on civil liberties. I am a libertarian and am extremely concerned about the erosion of our freedoms and civil liberties.”

But that’s not going to stop Opik from enjoying himself while he’s at it. “I think you can be dead serious about politics and yet do it with a smile”, he argues. “I think that some of my colleagues ought to lighten up a little bit, in all parties, and recognise that you can get great results and still have a good time. And if I have provided a bit of colour and a bit of character to the public image of MPs,” he muses, “then I hope that is regarded as all for the good.”

It’s a funny old world. With a soaring public profile, seemingly his pick of TV’s most glamorous women, and a stab at one of his party’s top jobs, all aiding him in making that all-important difference, Lembit may well be having the last laugh.

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