West Ham United have secured a 99-year deal to move to the Olympic Stadium in Stratford, it has been confirmed.
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Speaking at a press conference in the Olympic Park, the London Mayor Boris Johnson said it meant the venue would now "be the home of a great London football club".
The Hammers will move into the East London stadium, the centrepiece of the 2012 Games, from 2016 after conversion work costing up to £190 million has been carried out to make it suitable, and will pay £2 million a year in rent.
The move was finalised after West Ham said they would increase their contribution to the funding of the project by £5 million, bringing it up to £15 million.
The Treasury will put in around £60 million and West Ham will be "key tenants", meaning they are the most regular users of a facility that will also host events including athletics and live music.
Major work to the stadium will see retractable seating installed, meaning it can be switched back to being suitable for athletics, and the roof extended. It will have a football capacity of 60,000.
Johnson said: "This was the deal they said could never be done. I am very pleased to announce that this fantastic stadium will not only host community sport, rock concerts and athletics - it will also be the home of a great London football club.
"After a massive negotiation that went well into extra time, I want to pay tribute to both teams for a deal that is great for West Ham United, for London and for football."
In a joint statement, Hammers co-owners David Sullivan and David Gold said: "It's fantastic for everyone at West Ham United that, at last, all the club's hard work over the past three years has paid off.
"Since we came to West Ham in 2010, we have had a vision to really take the club forward so we can compete on the pitch at the highest level.
"Today's decision offers us a real platform to do this, and we are fully committed to making it a real success.
"We understand the responsibilities that come with calling the nation's iconic Olympic Stadium our new home. It is an honour we will take on with pride.''
Vice-chairman Karren Brady said the club was looking forward to working with fans to "create a stunning new home that befits the pride, passion and tradition that the world associates with West Ham United".
The London Legacy Development Corporation (LLDC) named West Ham as preferred bidders three months ago, but issues surrounding the funding of work to the stadium meant their move there was not a certainty.
As part of the agreement, Sullivan and Gold will pay a one-off windfall back to the LLDC if they sell the club - which will increase in value with the Olympic Stadium move - within the next ten years.
Earlier this month, Leyton Orient chairman Barry Hearn demanded a judicial review of the Olympic Stadium bid process, saying it denied his club the chance to make an effective case.
Hearn wants League One side Orient to share the venue, and the Brisbane Road chief has begun legal measures to have the decision to allow the Hammers to move in thrown out.
He said he believed the LLDC bidding process did not provide "for teaming, which is for all parties to share the stadium".
Hearn said he believed the decision could be overturned and that the announcement of West Ham as anchor tenants may have been premature.
"We think today's announcement is jumping the gun," he said. "The decision of the High Court will concern whether the bidding process rules were followed by LLDC. We say they weren't."
He said he was unhappy with the terms of West Ham's agreement, arguing that it meant the Hammers were being "sponsored by the government".
"This is a David and Goliath [situation] and I know everyone would rather I went away, but the sad news is that I'm not," he added.
"We've got a little tiny community football club being steamrollered by bureaucracy. If anyone needs help, which is surely the whole point of the Olympic legacy, it has to be the local club."
The stadium switch will see West Ham leave Upton Park, where they have played since 1904 and which is around three miles from the Olympic site in Stratford.