Bosses of P&O Cruises are already showcasing their £500 million new liner Britannia more than a year before the 141,000-ton vessel enters service.

Keen to promote their biggest-ever project, P&O have produced a video displaying what the 3,600-passenger liner will look like.

Boasting the biggest spa ever on a cruise ship, Britannia is being built at the Fincantieri shipyard at Trieste in Italy and the vessel will enter service in spring 2015.

To be based at Southampton, the Britannia will feature a startling atrium with a three-storey spiral staircase.

The company boasts that its cabins will be ultra-modern and there will be four swimming pools containing, in total, more than 61,000 gallons of water.

The interior is being designed by London-based Richmond International which specialises in hotel designs. Recent work has included upgrading one of the world’s most luxurious properties, the Sandy Lane hotel in Barbados.

Almost 335 metres in length, Britannia is being skippered by Captain Paul Brown who has been with P&O Cruises since 1996 and has been the captain on a number of the company’s ships including Aurora, Oriana and Ventura.

The company promises that the new ship will combine the best of the old with innovative features.

This will be the third P&O ship to bear the name Britannia.

The first entered service in 1835 when the company was called the General Steam Navigation Company. The second became operational in 1887 to mark the Golden Jubilee of Queen Victoria.

Many now associate the name Britannia with the now-decommissioned Royal Yacht. P&O chiefs have been somewhat coy about whether they checked with the Queen whether it was all right to use the name, but they have indicated that everyone is fine about it.

It is likely that a member of the Royal Family will be asked to officially name the new Britannia at a ceremony in Southampton in spring 2015.