The Tower of London has been partially closed after a display case containing Crown Jewels was defaced by protesters, police said.
Police were called shortly before 10:00 GMT on Saturday after four protesters threw custard onto the case containing the Imperial State Crown, before two protesters left the scene.
The Metropolitan Police said in a statement four people had been arrested on suspicion of criminal damage and taken into custody.
The Tower’s Jewel House has been closed to the public while the police investigation continues, the force said.
