Joined by two fellow campaigners, Martin Matthews, of Middlemead Road, Bookham, climbed the 12th-century fortified gateway on Saturday, September 12, before lowering the Queen’s Standard flag and replacing it with a tea towel.
On his Facebook page, Mr Matthews later claimed it was the ‘first siege of the tower since 1746’.
After unfurling a banner that read Stop the War on Dads, the three spent five hours on the monument between 12pm and 5pm.
Mr Matthews, 48, said: “Stunts like this are a bit of a laugh, we’re mocking and ridiculing the injustice. But there’s also a serious message behind it too.
“We would like to see parental alienation become a criminal offence, and raised to the status of child abuse.
“These days there’s such a high proportion of dads who do not live with their children that it’s almost abnormal to have a father in the house.
“But fathers have been campaigning on this issue since 1989 and gotten nowhere, so at this point it’s just about having fun with it.”
Describing it as a ‘good day had by all’, the plumber donned a Batman costume, while one of his companions was dressed as Humpty Dumpty.
They were also joined by two other activists, who remained on the ground, and their families.
Last year Mr Matthews became embroiled in a legal battle with Mr Grayling after being found guilty of causing criminal damage to the then-Justice Secretary’s roof.
Mr Matthews was fined £100 and ordered to pay £200 costs and a £20 victim surcharge.
Referring to the incident, the plumber took to Facebook to write: ‘I’ve well and truly learnt my lesson, I will never ever do anything like this again, how utterly irresponsible, I am so sorry’.