The latest nuclear submarines to roll off of the BAE Systems Barrow shipyards are the first two of the new nuclear-powered Astute class attack submarines.
All seven of those originally ordered have survived the recent Defence Review.
HMS Astute is 97m long and displaces 7,800 tonnes,the equivalent of 1,000 London buses.
Being totally self-sufficient, there is no theoretical limit to her submerged range or time spent underwater. Its normal complement is 98 officers and men, though it can carry 109. It has six weapon tubes, and carries Tomahawk cruise missiles and Spearfish homing torpedoes.
The Astute houses all the latest communications and information-gathering technology, including a sonar system that can scan an area 3,000 miles across.
To hide its own sonar signature, it is sheathed with over 39,000 acoustic tiles. It has an official underwater speed of 29knots.
The submarine has come along way since the days of HMS Holland 1, which was the Royal Navy’s first submarine, built at Vickers’yards in Barrow in 1900.