The group was awarded the contract by the Ministry of Defence (MoD) along with BAE Systems, which manages Portsmouth Naval Base and secured a £600m contract.

The agreement has safeguarded 4,000 jobs at Devonport Naval Base, with 1,500 and 2,000 at Clyde and Portsmouth respectively.

"This huge investment in our naval bases will directly sustain more than 7,500 jobs and skills across the UK and ensure that the Royal Navy’s fleet of 56 warships and submarines are in the best possible condition and available for operations," said defence minister Michael Fallon.

"Following the £3.5bn Scout armoured vehicle contract, this is the second biggest defence contract placed by this government and reflects our commitment to giving our armed forces what they need to keep Britain safe."

Bernard Gray, MoD’s chief of defence materiel, added: "These contracts are another example of how MoD is delivering on its major procurement programmes and finding both the right deal for the armed forces and driving down costs.

"The three naval bases in the UK play a vital role in the defence of this country and in the economic well-being of the regions in which they are located".