Defence firm BAE Systems will spend over £300m on a redevelopment of its submarine building site at Barrow-in-Furness.
The eight year scheme, which will employ 850 contractors at its peak, includes both new build and refurbishment.
Demolition work begins in April.
The work helps the companyrto prepare to build the replacement of the Royal Navy’s Vanguard class submarines, which remains subject to final approval by the government. If approved the first of the new submarines should be in service in 2028.