The First Sea Lord, Admiral Sir Jock Slater, represented the Queen at the commissioning ceremony of the �154m ship, which featured a fly past by Sea King, Lynx and Gazelle helicopters, a Hercules transporter and two World War II Swordfish aircraft.

HMS Ocean's commanding officer Captain Bob Turner said: "Commissioning day marks the end of years of building, fitting out and trials.

"It is the most important day in the life of HMS Ocean so far and the first chance to show off our new ship to our families and friends."

Multi-tasking role

Royal Navy spokesman Lieutenant Commander Bob Wilson said that HMS Ocean's first job as a navy ship is to sail to the Caribbean at the end of October for warm weather trials.

"We have to ensure that the ship's air conditioning, electronic equipment and general machinery works where there is a high ambient temperature," he said.

"Ocean will then sail to Belize and go through several evolutions, including embarking 500 commandos and equipment, before returning to the UK for Christmas."

It has already carried out more than 900 test landings of various aircraft.

HMS Ocean was conceived during the late 1980s Strategic Defence Review, which sought to adapt the Royal Navy from a Cold War deterrent force focused on a single threat to a new, global and flexible role.

Extra range

The 21,000 tonne, 208m long ship, officially described as a 'landing platform helicopter ship', is designed to "insert and extract" soldiers for peacekeeping, humanitarian and anti-terrorist missions.

Lieutenant Commander Wilson said: "The landing craft and helicopters with which Ocean is equipped can deliver men to shore from 150 to 200 miles out at sea, or from the shore it can place them a comparable distance inland.

"It's the first time we've had something with quite this range."

HMS Ocean can deploy up to 800 men using four large landing craft and 12 medium-support helicopters, principally Lynxes and Sea Kings. It can also carry up to 15 Sea Harrier attack aircraft.

Launched on 11 October 1995, HMS Ocean was built by Kvaener Govan in Glasgow, before sailing to Barrow-in-Furness for fitting out and finally arriving in Portsmouth for a final bout of remedial work.

In February 1997, the ship was christened by the Queen and the Duke of Edinburgh, becoming the sixth Royal Navy vessel to bear the name Ocean.

The commissioning means that HMS Ocean officially enters Royal Navy service, and it will replace two decommissioned amphibious assault ships, HMS Bulwark and HMS Albion.

Facts about HMS Ocean