The Ministry of Defence today defended the actions of Prince William who used a helicopter training exercise to fly himself and his brother to a stag do.

The young royal, who is on an attachment with the RAF, piloted a Chinook to London on Friday, picked up his sibling Prince Harry then travelled to the Isle of Wight for the social event.

The MoD stressed that the sortie was always planned as part of William's training and included all the elements being tested - flying in busy air traffic, crossing water and landing in an enclosed helicopter pad.

Hours before the flight the Prince, 25, received his RAF wings from his father the Prince of Wales at a ceremony at RAF Cranwell in Lincolnshire attended by William's girlfriend Kate Middleton.

An MoD spokesman said: "The Prince's training was designed to give him an insight into the many roles of the Royal Air Force.

"Having spent a week under instruction with a Chinook helicopter squadron Prince William flew a legitimate training sortie which tested his new skills to the limit.

"Flying at low level Prince William piloted the heavy support RAF Chinook helicopter through the busy London flying lanes to a helicopter landing site in Central London before departing the lanes to the South West, making a water crossing and an approach to a civilian airfield routinely used by Chinook squadrons."

William's instructor, who was not named by the MoD, said: "Prince William showed natural piloting skills and an ability to pick things up quickly.

"His final flight tested his burgeoning flying skills to the full and he performed very well indeed."

The Princes - both officers in the Household Cavalry regiment - flew to the Isle of Wight to join Princess Royal's son Peter Phillips who is getting married next month.

They were pictured in the Sun newspaper looking relaxed with their cousin who was made to hold a doll during the stag weekend.

William is coming to the end of a four-month attachment with the RAF and in the coming weeks will visit some of the service's frontline units.

In May, he will undertake a number of official engagements followed by some leave before beginning an attachment with the Royal Navy at the beginning of June.

The secondments are part of a "familiarisation" exercise to help the Prince understand all the services, as he will one day head the armed forces.