A Fathers 4 Justice campaigner who climbed on to the roof of deputy Labour leader Harriet Harman's home has been arrested, police said today.
Another man, Jolly Stanesby, remains on the roof of the Cabinet Minister's house in Herne Hill, south London after an all-night vigil, Scotland Yard said.
"A 49-year-old man who came down from the roof is in custody. A second man remains on the roof," a police spokeswoman said.
The pair, wearing superhero costumes, yesterday unfurled a banner reading "A father is for life, not just conception".
The group said they wanted to highlight the fact that fathers were being made redundant, emotionally in the courts and now biologically in the new Human Fertilisation and Embryology Bill.
Ms Harman, the Minister for Women and Equality, remained inside yesterday for over seven hours but eventually emerged to announce she was leaving until the protest was over.
She said: "We are going to move out and stay somewhere else. I don't think it's fair for police resources to be tied up outside my house by this demonstration."
During their protest Mr Harris and Mr Stanesby demanded a meeting with the Cabinet Minister, claiming she had refused to see them.
But Ms Harman denied this and said they could have attended her regular Friday constituency surgery at Southwark Town Hall two days earlier.
She said: "They have said this is because they want a meeting but I checked with my constituency office and they haven't requested a meeting.
"I checked with my ministerial office and they haven't requested a meeting there."
Fathers 4 Justice founder Matt O'Connor responded by saying he had asked Ms Harman for "urgent talks" over a year ago through his local MP in Winchester, Lib-Dem Mark Oaten.
He said: "She wrote back and refused, as did other Ministers, such as Peter Hain.
"We have a duty of care to our kids to address the elephant in the room that is mass fatherlessness and the catastrophic consequences it has on our children."
The two protesters said they intended to remain on the roof until Ms Harman read Mr Harris's book about his child custody battle, Family Court Hell.
Police established a cordon around the house and tried to persuade the men to come down, although Fathers 4 Justice said the pair had enough supplies for a week.
Speaking by mobile phone from the roof, Mr Harris insisted it was a peaceful protest but raised questions about Ms Harman's security arrangements.
He said: "All we did was push open the gate, which wasn't even locked, put a ladder up and climbed up.
"In this time of heightened terror alerts I can't believe Harriet Harman has such lax security. My house is more secure than this."
The protest was the latest in a long line of high-profile Fathers 4 Justice stunts.
The most notorious incident involved activist Guy Harrison throwing a flour bomb at former prime minister Tony Blair in the House of Commons in May 2004.
Mr Blair was unhurt, but speaker Michael Martin immediately suspended the sitting halfway through Prime Minister's Questions.
Fathers 4 Justice was shut down in January 2006 after extremist sympathisers were accused of plotting to kidnap Mr Blair's son Leo.
But it was relaunched four months later when campaigners invaded the live broadcast of the National Lottery draw.
Members dressed as superheroes have previously raised awareness of their cause by scaling high-profile buildings, including Buckingham Palace.
Mr Stanesby and another activist were fined after climbing Stonehenge dressed as cartoon caveman Fred Flintstone in February last year in protest about comments made by Tory leader David Cameron on absent fathers.
Fathers 4 Justice said it had been left with no choice but to resume its campaign of direct action and civil disruption because of the Government's "point-blank refusal" to meet its representatives.
Mr O'Connor will lead a "Fatherless Day" demonstration at the Trooping the Colour ceremony in London on Saturday, the group said.