British shipbuilding receives a boost as Boris Johnson names the yard which has won a deal to build Royal Navy frigates.
The Prime Minister will unveil the successful bidder to construct five Type 31 warships to help replace the ageing Type 23 Duke-class vessels.
Work will start before the end of this year and the first ship will set sail by 2023.
The PM will unveil the winning bidder when he visits a ship on the Thames to mark London International Shipping Week.
Mr Johnson said: "This is an industry with a deep and visceral connection to so many parts of the UK and to the Union itself.
"My government will do all it can to develop this aspect of our heritage and the men and women who make up its workforce, from apprentices embarking on a long career, to those families who have worked in shipyards for generations.
"I look forward to the restoration of British influence and excellence across the world's oceans.
"I am convinced that by working together we will see a renaissance in this industry which is so much part of our island story - so let's bring shipbuilding home."
Unions welcomed the announcement and urged the PM to commit to building Fleet Solid Support vessels in the UK too.
Unlike warships, which can only be manufactured in the UK for national security reasons, the supply vessels could be built abroad.
Companies from Italy, Spain, Japan and South Korea are in the running for the £1.5billion contract, with a UK consortium also shortlisted.
GMB general secretary Tim Roache said: "All work for our struggling yards is welcome but this particular order was always reserved for the UK.
"If ministers are serious about saving jobs and skills in this country then they must also keep the £1.5billion Fleet Solid Support contract with our yards instead of punting that vital work overseas."
The three vessels will resupply destroyers, frigates and aircraft carriers with ammunition, explosives and food.
The British team competing for the contract includes Babcock, BAE Systems, Cammell Laird and Rolls-Royce.
The winner will be revealed next year.
Confederation of Shipbuilding and Engineering Unions general secretary Ian Waddell said: "It is no exaggeration to say that the future of the UK's shipbuilding industry hangs in the balance.
"Five Type 31 ships will not be enough to save tens of thousands of jobs in the yards and their supply chains, but rolling the build together with FSS would give all the UK yards work, allow investment for the future and open the door to the ambitious plans the Prime Minister has outlined.
"Without FSS, those warm words about a bright future are nothing but hot air and bluster and that won't pay the bills."
Prospect general secretary Mike Clancy said: "It is welcome that this announcement has finally been made following damaging delays from government that caused huge uncertainty for the industry.
"Events in the Gulf this summer have shown that 19 frigates should be an absolute minimum for the Navy, so this first order of five warships must be followed up by further orders.
"This will maintain the drumbeat of production and make sure further capability gaps do not occur.
"This Government has a lamentable record on shipbuilding, with yards closing and skills lost.
"These frigates were always going to be built in the UK, but workers need a cast iron guarantee from the Prime Minister that new naval support ships will also be built in our yards and UK workers will not be left high and dry while vital work is sent abroad."
Meanwhile, it is unclear whether the winning firm for the Type 31 contract will build the boats for £250million each - the price tag originally demanded by the Government.
The Mirror told a year ago how only one company tabled a bid matching the planned cost - forcing ministers to delay the project.
The Type 31 programme will support more than 2,500 jobs across the UK.
Defence Secretary Ben Wallace said: "The Type 31 frigates will be a fast, agile and versatile warship, projecting power and influence across the globe.
"The ships will be key to the Royal Navy's Fleet to keeping peace, providing life-saving humanitarian aid and safeguarding the economy across the world from the North Atlantic, to the Gulf, and in the Asia Pacific."
Naval chiefs have repeatedly accused the Tories of running down the military and called for more warships.
The UK has just six destroyers and 13 frigates.
The Type 23 frigates are being phased out and will be replaced by eight Type 26 Global Combat Ships and the Type 31s.