The street artist's latest work appeared at the Royal Courts of Justice in London on Monday and was immediately covered up by Metropolitan Police officers.

The force is now investigating the graffiti, which is on an external wall of the Queen's Building, as potential “criminal damage”.

It means Banksy, who has remained anonymous for more than 25 years, could finally be unmasked as he would be required to publicly disclose his name if brought to court.

The artwork, which shows a protester holding a white picket sign spattered with red paint, has now been concealed by large sheets of black plastic and two metal barriers.

Less than 24 hours after it first appeared on the Grade I-listed building, HM Courts and Tribunals (HMCTS) confirmed it would be removed.