SEPTEMBER 20, 2012: HMS Ambush, the second of the Royal Navy’s new Astute Class attack submarines, sailed into HM Naval Base Clyde to begin sea trials.

The 7,400-tonne submarine sailed from BAE Systems Maritime Submarines at Barrow-in-Furness, where she was built.

The seven Astute Class vessels planned for the Royal Navy were the most advanced and powerful attack submarines Britain had ever sent to sea.

They featured the latest nuclear-powered technology, which means they never need to be refuelled and can circumnavigate the world submerged, manufacturing the crew’s oxygen from seawater.

Philip Dunne, minister for defence equipment, support and technology, said: “Ambush’s arrival at her home port to begin her sea trials marks a key milestone in the Astute Class submarine programme and is testament to the skills of those involved in the UK’s world class submarine-building industry.”

The Astute Class was quieter than any of its predecessors and has the ability to operate covertly and remain undetected in almost all circumstances, despite being 50 per cent bigger than the Trafalgar class vessels they were designed to replace.