HMS Vanguard was the first of the four submarines of her class she carried out the first Trident missile test firing in May 1994 and the first operational deterrent patrol in 1995.
Pictures of Vanguard and her sisters do not do the boats justice – at a fraction under 150 metres the submarine is almost the same length as St Paul's Cathedral.
Each V-boat has two captains and two crews, port and starboard, which means the duty crew are out keeping the UK safe while their opposite numbers, back at the boat's base at Faslane in Scotland, train or take leave.
Offering reassurance to British interests and allied nations by providing an ongoing Royal Navy presence.
Nine ships have been named Vanguard before the current vessel – the first submarine. First a 31-gun galleon launched at Woolwich in 1586 which took part in the defeat of the Spanish Armada.
She was rebuilt at Chatham in 1615, making her half as big again and mounting 40 guns, and a further rebuild 16 years later back at Woolwich allowed her to carry 56 guns. She was sunk in June 1667.
Vanguard no.2 was a 2nd Rate 90-gun ship of the line launched at Portsmouth in 1678. The three-decker tipped over in the Medway in November 1703 but was rebuilt in Chatham six years later.
In the summer of 1728, following another rebuild, she was renamed Duke and served on until she was broken up in August 1769.
Another Vanguard – a 3rd Rate of 70 guns, launched at Cowes in April 1748 and sold in April 1774, while the fourth barely registered - a four-gun Spanish tiddler captured in 1780, sold three years later.
The fifth Vanguard, a Deptford ship, was launched in 1787 as, a 3rd Rate 74, and won a special place in the annals of the Royal Navy as Nelson’s flagship at the Battle of the Nile.
She was broken up in 1821 after nine years as a prison ship and powder hulk.
Her successor was a similar-sized ship bearing four guns more, launched at Pembroke Dock in 1835, she was an experimental design intended to demonstrate greater speed and stability.
She was renamed Ajax to release the name Vanguard in 1867 and broken up eight years later.
The seventh Vanguard was an ironclad battleship launched at the Laird yard on the Mersey in 1870. She spent much of her life as guardship at Kingstown (now Dún Laoghaire) in Ireland.
Vanguard was rammed and sunk by her sister HMS Iron Duke County Wicklow in September 1875 with no loss of life (except, reportedly, the Captain’s pet dog).
Vanguard number eight was a St Vincent-class launched by Vickers at Barrow in 1909. She came through Jutland unscathed in 1916.
July 1917 she sank almost instantly following an accidental explosion while at anchor in Scapa Flow; more than 800 men died in one of the worst single accidents in the UK’s history.
The ninth Vanguard was the last battleship to be built by the Navy. Although laid down in 1941 she was not commissioned until a year after the war ended and remained in service until 1954.
In 1956 Vanguard became flagship of the Royal Navy Reserve but within three years she was slated for scrapping.
She was towed from Portsmouth Harbour in August 1960 - though she didn't go without a struggle, wedging herself against the Still and West pub until tugs could free her.
She was the first of the four Vanguard submarines to be launched on 4 March 1992.