They have since been adapted to play a support or offensive role in joint operations such as Nato’s Kosovo conflict operations and attacks against the Taleban in Afghanistan.

The Trafalgar class submarine carries US-made Tomahawk cruise missiles with a 1,000-mile (1,609 kilometres) range.

One of the major military advantages of a submarine is that they can be deployed ahead of a main fleet. Once in position off an enemy coast they can deny opposing fleets access to the sea by picking off any ships as they leave port.

Trafalgar class submarines are capable of attacking surface vessels and are armed with Spearfish torpedoes and sub-Harpoon missiles for that purpose.

Attacks can take place from up to 50 miles (80 kilometres) away. Fleet submarines have a third role, developed during the Cold War, to hunt down and destroy enemy submarines.

The UK has seven operational Trafalgar class submarines and five smaller Swiftsure-class vessels which perform a similar role.