Defence giant BAE Systems is to invest more than £300 million at one of its sites, at Barrow in Cumbria, to "transform" its submarine building capabilities.
An eight-year programme at Barrow will lead to the employment of 850 contractors to build a new state-of-the-art manufacturing facility.
BAE is the prime contractor in the Astute programme, designing and building seven nuclear submarines. The first two have been handed over to the Royal Navy.
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."
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 £300 million 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."