Focus: 'I would give all this up just to see my daughter': the millionaire who stormed the Commons

Julia Stuart meets the maverick who is willing to swap his mansion for a prison cell in pursuit of justice

Outwardly, Harrison has everything. A multi-millionaire businessman at 38, he owns an eight-bedroom pile overlooking a private lake, where he jet-skis before hopping into his hot tub. When he's bored with that, there are tennis courts, quad bikes, a pool and that all-important helicopter-landing pad.

Inwardly, though, Harrison is suffering, and last week - not for the first time - he brought his plight to public attention.

The Fathers 4 Justice campaigner who gained notoriety by throwing powder-filled condoms at Tony Blair during Prime Minister's Questions last year resumed his protest by climbing to the top of Westminster Hall and remaining there for five hours.

Not only is Harrison immensely rich - his businesses include fisheries, farming, property and a company that produces digital photography and floor plans for estate agents - but he has also won the heart of Emily Blount, 27, the striking blonde sister of the pop star James Blunt.

She has just moved in following a 10-month courtship. Under her watchful eye a decorator is giving the bachelor pad some much-needed style. But there is one bedroom in the mansion that remains untouched. In it is a tiny bed covered with soft toys, which belong to Harrison's daughter.

Stuck to a wall are cards celebrating her first and second birthdays. But the girl outgrew the bed years ago and Harrison no longer knows how tall she is. For he hasn't seen his daughter, now aged seven, for four years.

"I'd give up all this to see her," he said, gesturing to the house and grounds. "It just goes to show that money can't buy you happiness."

Harrison's daughter is the most important thing in his life. He says he has lost contact with her because her mother - his ex-fiancée - refuses to comply with court orders granting him access. Hence his Westminster Hall protest. Once on a precipice, he unfurled a banner and sat there for five hours talking to the media on his mobile phone while hoping not to be shot by police marksmen.

Emily watched below, fully supportive but terrified. After climbing down, Harrison was taken to Charing Cross police station where he was interviewed. He will have to wait until 18 October to know whether he will be charged. Aggravated trespass carries a three-month prison sentence.

"I'm absolutely terrified at the thought of going to prison, obviously. It's a horrible concept," he said, sitting at his kitchen table next to the Aga. "You would hope they would look at it on its merits. It wasn't in any way aggressive and we are trying to raise awareness of what's going on."

An adrenalin junkie who thrives on sky-diving, performing aerobatics in his helicopter and playing polo, Harrison shows no sign of joie de vivre as he talks flatly about losing his daughter and the subsequent 18 months of contemplating suicide.

After a "very difficult on/off relationship" for five or six years with his then partner, the couple got engaged in the hope that it would bring them closer. When it failed to do so, and the relationship was on the verge of collapse, she fell pregnant.

The courts granted Harrison access for one day a week and every other weekend, which worked, though acrimoniously, for three years. His ex-fiancée then moved out of the area and married. While she has never publicly given her side of the story, Harrison claims she wanted him out of her life and so refused to allow him to see their daughter.

"I think it was because she had a new family and felt that the father was totally dispensable. She decided it was much easier to remove me from my daughter's life and sadly has the power of judge, juror and executioner all in one. I think we went to court 37 times."

At one stage she accused Harrison of abuse when a scratch appeared on their daughter's torso. "When the judge saw the evidence he said it was absolutely ridiculous and that it could be a bramble scratch and threw it out of court," said Harrison.

"It was terrible. Then you go to a contact centre to see your child where you are treated like a paedophile. You are put under scrutiny permanently. I took her by the hand to take her to the loo only to have a security guard slap me on the back and say, 'Mr Harrison you do not take the child to the loo on your own'. You're guilty until proved innocent and you can never prove yourself innocent."

He believes his relationship with his ex-fiancée turned so sour because he rejected her. "I think she was so committed to loving me, which is very flattering but sadly wasn't reciprocated, that she began to hate me with the same passion that she loved me with."

The consequence of losing contact with his daughter was a depression that was "just astounding - as though someone has killed the closest thing to you.

"I'm a very positive, upbeat person who likes very much living and doing everything possible in life. When I was 16 my father died in my arms from a heart attack. I think losing your daughter is 10 times worse and I was extremely close to my father." Their acrimony has not only cost him emotionally but also financially. He has spent more than £50,000 in legal fees, securing three court orders allowing him access.

"My ex-fiancée realised that she doesn't have to comply with these court orders and when they got more and more ferocious, saying that you are going to go to jail if you don't, she said fine, put me in jail."

Much to Harrison's fury, the court never followed through with its threat. "I think she should be put in jail because she has flouted judges and various court orders saying you must let him see your daughter. That has got to be wrong. You put a mother in jail for not paying her television licence."

Harrison doesn't regret his powder-bombing of the PM in spite of being fined £600, gaining a criminal record, and losing 30 per cent of his business. "I have a criminal record linked to terrorism.

"I had to shut down my companies in America and Australia because I'm not allowed to go there," he said. It is far from the last we have heard of Harrison. The public campaigning won't stop until court orders are upheld and there is a presumption of equal access for parents.

"I can go and try and get another court order, but having got three and them not being worth the paper they are written on there's no point getting any more. So I need to change the law.

"I think there were 2,000 people evacuated last week from Westminster and that creates a cost for the Government. Fathers 4 Justice will do it until we have cost the country billions of pounds."