By Kevin Keane
Fife reporter, BBC Scotland news website
The 65,000 tonne vessels will be the largest warships built in the UK
The dockyards of Rosyth would be "on a rundown to closure" without the boost from a £3bn aircraft carrier contract, unions have claimed.
The deal gives the go-ahead for the giant 65,000 tonne carriers to be assembled in Fife.
It will secure the jobs of 1,250 people who already work at Babcock Marine and create up to 350 more.
The vessels, named HMS Queen Elizabeth and HMS Prince of Wales, will be the biggest warships ever built in the UK.
Chairman of the dockyard industrial joint council, Raymond Duguid, told the BBC Scotland news website: "We are delighted that we have got the ink on the paper. We have always known this was going to happen, we were quite confident having spoken to ministers.
"The 1,250 people here have now got the opportunity to maintain their careers. We took on 50 apprentices last September. They are now in the yard. We have just completed interviews for another 50."
Mr Duguid added: "If it wasn't for this then the dockyard would be on the rundown to closure, it would be that stark. We needed to work hard for this."
In February, Babcock awarded a £35m contract to modify a dry dock in preparation for the contract coming to Fife.
It will see the construction of a 75m crane, the biggest in the UK.
But the final signing of the Government contracts had been hit by delays.
Tony Martin, chairman of Fife Council's environment, enterprise and transportation committee, said: "I know people think it was a certainty but I do not think it was.
"The defence structure has pressure on it and people who just thought this is going to come anyway were being complacent.
"You can tell that the defence budget is overcharged because we have been fighting two wars and there is a need for more than just two aircraft carriers.
"One does not want to contemplate what would have happened if we had not got the contract."
Already, about 120 design engineers are working on the project in Rosyth and the Fife shipyard will be the first to set work on construction.
Number one dock is currently being refurbished for the giant carriers
John Howie, Managing Director of Warships for Babcock Marine, said: "We start cutting steel later this year. We are the first yard to do that. We manufacture the aircraft lifts which lift the planes on to the top of the ship."
Although jobs will increase to about 1,600 on the site, Babcocks has no plans to bid for similar contracts in the future.
"We are not setting ourselves out to be a major ship building company. It is an unusual project for us and we are involved because it is too large for any one company," said Mr Howie.
Despite delays in signing the contract, he insisted the consortium was fully on track.
"I would not like you to get the impression that there has been a major delay because the work has been going on.
"What happens in the yard today would have been happening today whether the contract was signed or not. This is just a matter of formalising the contract."
When it reaches its peak, it is estimated there will be about 6,000 people working in the Rosyth dockyard.
The majority of those who will come to work from other parts of the UK, including shipbuilders from the Clyde.
But it is hoped Babcock can increase its core workforce to about 1,600, a number which is will hope to maintain once the carriers are built.
Lib Dem MP for Dunfermline and West Fife, Willie Rennie, said: "My first and short reaction is 'at last,' although I probably won't believe it until I see the ink on the contract myself.
"I want to make sure local people experience the opportunities by being employed in the yards. I am talking to Scottish Enterprise about that."
The MP went on: "The question is, what about after the carriers have gone? Is there going to be a big boom and then a bust? We need to make sure not by using this as an example of what Rosyth can do.
"But at the end of the day, this is very good news for Rosyth and West Fife."