Prince William had petrol bombs thrown at him during a visit to Gravesend, it has been claimed.

The 31-year-old Duke of Cambridge is understood to have visited Gravesend’s Police Specialist Training Centre on the waterfront, just off Mark Lane.

Kensington Palace, which the prince, his wife Kate and son George have just moved into, told the Messenger that the visit was ‘private’ and they could not comment on the speculation.

The secret visit was apparently revealed by the daughter of one of the officers involved in the exercise, who wrote on a social network: “My dad threw a petrol bomb at Prince William – what a claim to fame”.

The training centre offers officers specialist training in firearms and has a mock-up of a town, complete with roads, houses and shops.

Prince Charles made an official visit to the same training centre in 2009, when he watched mock rioters clash with police.

The prince cracked jokes with the firearms officers and went on to say: “It is tremendous what you are doing here. You are all highly-trained experts.”

The £50 million training centre opened in 2003. Several films and TV programmes have been filmed there, including episodes of The Bill and the film Incendiary, starring Ewan McGregor.