Tourists were impersonated by a group of anti-monarchy activists who managed to break into Buckingham Palace carrying out the “first” protest inside the monarchy’s house, reports CNN.

“The group of local activists from different parts of the UK visited the palace as touristsbefore standing in the Great Hall,” Britain’s biggest anti-monarchy group, Republic, said in a statement.

The group posted a photo showing protesters standing inside the palace wearing T-shirts that read “Not my king”.

This is the latest in a series of targeted actions in promoting the debate on the future of the monarchy,” Republic said in a statement.

The group said six of the activists who took part were briefly detained by security before being led out the front gate.

Buckingham Palace told CNN it does not comment on security matters.