Two men have scaled Westminster Abbey in a Father's Day protest, New Fathers4Justice said.
The group said Bobby Smith from Stevenage and James Dennis from Bishops Cleeve, Gloucestershire, have scaled the church, opposite the Palace of Westminster in central London.
The group, which campaigns for the rights of fathers to see their children, said: "Father's Day is an emotional time for fathers denied access to their children."
The men unfurled three banners on top of scaffolding which stood against one side of the building.
One read "Parental Alienation" another read "Give me back Elmo" and another stated "Daddy's not giving up on you Elmo x x x".
Three uniformed police officers stood at the foot of the Abbey watching the protesters.
And bemused tourists stopped and took photos of the sight.
Mr Smith, 33, stood against David Cameron in the constituency of Witney in Oxfordshire in the general election having started his own party - Give Me Back Elmo.
The 33-year-old, who dressed as the Sesame Street character Elmo for his election campaign, claims he has been denied access to his two daughters, and is campaigning for a change in the way family courts work.
Speaking from the top of the scaffolding, he said: "We chose Westminster Abbey because it's such an iconic church.
"And because it's Father's Day - we haven't just done this on the spur of the moment.
"I stood against David Cameron in the general election. That was my last attempt to try and engage in political dialogue. He ignored me for the whole campaign.
"I have got two kids and I have no access at all to them. I haven't seen one of them for over two years, and before that it was supervised contact.
"Fathers' rights just aren't on the political agenda."
He said family courts do not treat fathers fighting for custody fairly.
He added: "Kids are much worse off without their fathers around. We can't sit back and let our children grow up without us."
The two men agreed to climb down off the Abbey after several hours, the campaign group said.