A millionaire fathers' rights campaigner who scaled the Houses of Parliament says he would do it all over again as he faces three years in jail for the stunt.

Guy Harrison, 38, who spent seven hours perched on a ledge above Westminster last September, said he was "bemused" by the prospect of his trial which starts on Monday and is expected to last five days.

If convicted the Steyning businessman may have to postpone his marriage to fiance Emily Blunt, sister of chart topper and former solider James Blunt. The pair are due to wed in Hampshire next June.

He said: "I have just got engaged and I have an engagement party at the end of this month but I might not be there for it."

He told The Argus he was unsure whether Emily, whom he met through auction website eBay two years ago, would be in at Southwark Crown Court.

He said: "We are going to play it by ear. The thought of spending three years in jail is putting more stress on my fiance than me. It is really upsetting her, which is quite understandable. I would like to think I won't get three years but the fact is we have got a judge who has everybody's lives in his hands."

Last year's Fathers 4 Justice protest was a birthday present for Mr Harrison's eight-year-old daughter, Izzy, who he has not seen in five years.

Asked if he would do it again Mr Harrison, who had never been arrested until he joined the campaign group, said: "Absolutely. All we are asking is to see our children. It is a basic human right we seem to be denied in this country. I am a responsible citizen and I am being treated like some kind of psychotic paedophile."

Mr Harrison is charged with two counts of causing a public nuisance and public disorder. He first hit the headlines in May 2004 after powder bombing the Prime Minister in the House of Commons with fellow campaigner Ron Davis, from Findon, near Worthing.

He also stormed the stage of the National Lottery with fellow members of Fathers 4 Justice earlier this year. He said: "Security is just as lax as it has always been. I believe we are making a very good point that terrorists could very easily carry out some awful atrocities.

"I really cannot comprehend why they are trying to put me inside for three years. A five-day trial with 22 witnesses is an absolute joke for sitting on the top of a government building for seven hours. I didn't hurt anybody and it was a peaceful protest. This is an absolute waste of tax payers' money."