A Fathers for Justice campaigner set up camp and unfurled a banner on top of Justice Secretary Chris Grayling’s home last night.
The protester, believed to be Martin Matthews of Great Bookham, climbed on to the roof in Ashtead with supplies at 9pm.
He appears to be mooning in one of the blurry photographs of the stunt.
Officers have erected scaffolding at the house and a police negotiator is currently speaking with the trespasser.
New Fathers for Justice sent these pictures earlier this morning
In a statement New Fathers for Justice said: “He has put up a banner which reads 'Mum and Dads United'.
“He has set up camp on top of the roof and has enough supplies to last several days. This is another protest to highlight the injustice parents face in the present family court system.”
Mr Matthews climbed onto the roof of the Epsom and Ewell MP’s constituency office in Barnett Wood Lane, Ashtead, on Fathers’ Day in 2013 and in October, 2012.
Yesterday he posted on Facebook: “Off to do a little one man protest because it’s the right thing to do.”
Last year he told the Epsom Guardian: "I will keep climbing on Chris Grayling’s roof until he changes his mind about things. It’s not unlawful or illegal to dance on somebody’s roof."
New Fathers for Justice said it wants parents to have equal contact with the child if they split up, an end to “forced adoption” and the abolition of a “undemocratic secret court system” in the family division.
Epsom resident Andrew Wills, who went past the house this afternoon, said he saw a dozen policemen, a specialist search unit van and three police cars there.
The protester appears to be baring his behind in this picture released by New Fathers for Justice
Mr Wills said: “It was a high police presence. I would defend the father’s right to protest but somewhere more public than an MP’s house would be more appropriate when you think of all the police time that takes up, to say nothing of the inconvenience to the MP’s family.”
A Surrey Police spokeswoman said they were called to the address at 12.15am this morning after a report of a trespasser.
She said: "Officers attended the scene and located a man who claims he is holding a protest. Police are closely monitoring the situation.
"Officers are speaking with the man who is currently on the roof of the property and appropriate updates will follow in due course."
Fathers' rights activists were arrested for camping on the roof of a gate at the entrance to London's Hyde Park for a number of days last week.