A £2.5 billion investment in UK nuclear submarines shows the Government's "unwavering commitment to keeping the UK safe and secure from intensifying threats", the Defence Secretary will say.

Gavin Williamson is due to announce that his department has signed a £1.5 billion contract to build a seventh Astute hunter-killer submarine for the Royal Navy, adding the attack boat will be called Agincourt.

Visiting BAE Systems' shipyard in Barrow-in-Furness Cumbria, Mr Williamson will announce £960 million worth of contracts have been signed to boost the second phase of construction for the UK's four nuclear-armed Dreadnought submarines.

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The multibillion-pound announcements will help sustain approximately 8,000 jobs in BAE Systems' submarine business, plus thousands more across the UK submarine supply chain, the Ministry of Defence said.

Mr Williamson will say: "This multibillion-pound investment in our nuclear submarines shows our unwavering commitment to keeping the UK safe and secure from intensifying threats.

"Agincourt will complete the Royal Navy's seven-strong fleet of hunter-killer attack subs, the most powerful to ever enter British service, whilst our nuclear deterrent is the ultimate defence against the most extreme dangers we could possibly face.

"Not only is this a massive boost for our armed forces, but it's huge for Barrow, the heart of sub-building in this country. Today's news supports 8,000 BAE Systems' submarine jobs, as well as thousands more in the supply chain, protecting prosperity and providing opportunity right across the country."

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Mr Williamson will also officially open a new £100 million sub-construction building in the Cumbria factory. He will unveil a plaque in front of workers to mark the opening of the Central Yard Facility building which will be used to outfit and test each section of the new Dreadnought submarines.

Defence Minister Guto Bebb will be in Derby, with the Rolls-Royce contract seeing more than 700 jobs sustained at their factory in the city.

Barrow and Furness MP John Woodcock welcomed the new contract.

He said: "Sealing the deal on Astute boat seven is a huge relief after the crazy moves to cancel it from certain quarters which would have thrown the supply chain into chaos.

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"A full complement of SSN submarines to secure our shores and protect British naval assets will be vital at a time when the subsea environment is becoming more and more contested with Russia greatly increasing its aggression.

"Big challenges remain to persuade the Treasury to give the larger Dreadnought programme sufficient upfront funding but this contract is very welcome and I am looking forward to joining the defence secretary on his visit to Barrow shipyard today."