A man was arrested at the National Gallery in London after he attacked John Constable's 19th century masterpiece The Hay Wain by gluing a 10cm photograph of a young boy to the oil painting.
AFP reports that protester Paul Manning is believed to be linked to campaign group Fathers4Justice.
The group campaigns for fathers to have fair access to their children following separation from their mothers.
The National Gallery said that there was no lasting damage to the 1821 work of art.
According to The Independent, a gallery spokeswoman said: "Conservation staff were on the scene very rapidly and the painting was removed for treatment.
"No damage to Constable's original paint occurred and there is no lasting damage to the painting."
The gallery is investigating the security breach but praised its "quick thinking" staff for intervening before more damage was done.
The incident coincided with a Fathers4Justice campaigner appearing in court accused of vandalising a portrait of the Queen in Westminster Abbey, the BBC reports.
Tim Haries, 41, from South Yorkshire, reportedly daubed the painting with spray paint on 13 June.
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