Defence giant BAE Systems will invest more than £300m to "transform" its submarine building capabilities at Barrow-in-Furness.
The eight-year redevelopment programme will employ 850 contractors to build a new state-of-the-art manufacturing facility for the Barrow-in-Furness yard, which built its first submarine in 1886 for the Ottoman navy.
It is the most significant investment in the yard since 1986 when BAE built the 25,000 square metre Devonshire Dock Hall, where submarines are built and stored, and includes the refurbishment of existing infrastructure and construction of new build facilities, including a 28,000 square metre off-site logistics facility to store submarine parts.
The announcement was scheduled to coincide with a visit by Conservative defence secretary Philip Hammond to shipyard, underlining the party's commitment to the £20bn program to replace the four ageing Vanguard-class submarines that currently carry the UK’s Trident nuclear deterrent.
Tony Johns, managing director of BAE Systems Maritime - Submarines, said: "Redevelopment of the site is fundamental to the future of our business and will ensure we stay at the forefront of submarine design, build, test and commissioning.
"This investment will provide a modern, 21st century environment for our employees to apply the unique skills and expertise that have delivered complex submarines to the UK Royal Navy for over a century.
"The Successor programme, to replace the Vanguard class submarines, remains subject to final approval in 2016, but it is vital we begin these improvements now in order to achieve the Government's target of having the first submarine in service by 2028."
The government has already spent £730m on assessing the Successor programme since 2011, including contracts worth a total of £350m that it awarded to BAE, Rolls-Royce and Babcock in 2012 to design the submarine.
Altogether it expects to spend £3bn on the assessment phase before a final decision on Trident is taken in 2016, after parliamentary elections. About 3,000 people are currently employed on the Successor programme.
Defence Secretary Philip Hammond said: "Barrow has a proven track record of designing and building submarines with a battle winning edge for the Royal Navy. The world leading engineering skills that are currently delivering the Astute class are vital to ensure we can deliver the submarines of the future.
"The next generation nuclear-deterrent submarines that will be built in Barrow will be the largest and most advanced submarines ever operated by the Royal Navy. The £300m of infrastructure work that will take place over the coming years will not only protect 6,000 highly skilled jobs at the site, but also provide hundreds of additional construction jobs."
The Barrow yard is currently busy building the nuclear-powered Astute class attack submarines, which cost on average more than £1bn each, and the firm said the steel has been cut on the seventh and final Astute class submarine.
BAE expects to start building the first Successor in September 2016, which will require the company to hire about 1,000 more people at the shipyard.
Renewing and maintaining Britain's overall submarine fleet is expected to cost £38bn over the next decade, representing a large share of the country's £164bn defence equipment budget, the defence ministry said last month.
The government also awarded BAE a five-year £23m submarine design services contract whereby it will provide analysis on technical matters and support design upgrades, principally for the Astute class submarines.