"We understand the responsibilities that come with calling the nation's iconic Olympic Stadium, which will be converted into a world-class football stadium, our new home, " West Ham joint chairmen David Sullivan and David Gold said in a statement.

WSJ: West Ham Gets Olympic Stadium

The country is awash with world-class grounds, including the FNB Stadium near Soweto.

BBC: An aircraft flies over the FNB Stadium

Williams has had one game since post-British and Irish Lions tour shoulder surgery - for Cardiff Blues against Ospreys - but is expected to take on fellow world-class openside Richie McCaw at the Millennium Stadium on Saturday.

BBC: We can beat All Blacks - Williams

"The excitement of the Magners League play-offs gave everyone a real lift and, with the move to our new training and medical centre at Scotstoun Stadium just a few days away, all three lads will benefit enormously training alongside some world class players in first class facilities, " he said.

BBC: Glasgow Warriors sign Edinburgh prop Ryan Grant