The medieval timbered Halls of Westminster played host to a high-stakes poker game to decide the next occupant of No 10.
And it was a game in which Nick Clegg needed some buy-in from the rest of the Liberal Democrats urgently.
The 49 male and 7 female Lib Dem MPs swept up the ancient staircase of Westminster Hall soon after 1pm, gathering for the second time in 48 hours.
Facts were thin on the ground: they knew only that while the prospect of a deal to install David Cameron as British Prime Minister appeared to be gathering momentum, there were few signs of the concessions they were demanding.
Under the Byzantine rules of the Lib Dems, designed to bind the hands of any leader, a rebellion by only 14 of the people in that room would be enough to put a stop to the Tory discussions.
Outside, former MP Lembit Opik was explaining this to the media, gleeful at another opportunity to appear on television.
Mr Clegg joined his party in the Grand Committee Room almost half an hour after the rest. Sitting in the middle at the microphone, he took questions for more than two hours.
While he and his team of negotiators insisted that they were making excellent progress, few understood exactly what this meant.
A limited number of Lib Dem MPs have been trusted with the specifics of the discussions. No documents have been circulated.
Despite huge goodwill towards Mr Clegg and his negotiators, some MPs found the early parts of the meeting frustrating as they struggled to work out what had happened.
"The team marched in, saying they have been granted comprehensive political reform. Someone said we had been given 99pc of what we wanted. But it didn't turn out to be quite as straightforward," said one.
Several baubles had indeed been dangled before them, but on the defining issue of voting reform, the promise was more limited.
It turned out that the only Tory pledge was to initiate a free vote on legislation for a referendum -- a measure likely to fall at the first hurdle and, therefore, unacceptable to most Lib Dem MPs.
The disappointment was clear, and although the mood never turned nasty, Lib Dem MPs made it plain that the Tory offer did not go far enough.
A passionate early intervention from Menzies Campbell, the former leader, carried particular weight.
The veteran -- whose friendship with Gordon Brown handicapped his own leadership -- urged his successor not to bind the party into a irrevocable deal with the Tories in an apparent bid for an eleventh-hour change of strategy.
Many others endorsed this point of view, hoping it would strengthen their party's negotiating position.
Others were concerned by the failure of the leadership to explain the detail on issues such as greater funding for schools -- stoking fears that the Tories might have 'out-negotiated' them.
By the end, almost three quarters of those present had spoken but the message was coming as one.
Mr Clegg must not close off the chances of a deal with Labour. And if an accommodation with the Tories appeared the best option, they insisted, the Lib Dems should demand "plenty" of jobs in the next government.
After the meeting, Mr Clegg dodged journalists, going down a glass lift and through the tourist cafe.
Within minutes, he was talking to Gordon Brown and 90 minutes later the Prime Minister announced that he was going to resign as Labour leader.
Last night some senior Lib Dems were congratulating themselves on a 'game-changer'.
"Clearly you get a better deal when you have the prospect of competing deals," he said. "The markets will know we're in the endgame on this. We've forced both parties into a clear stance. They'll all be wearing 'I agree with Nick' T-shirts soon."
The Lib Dems believe that they are cleaning up the pot in this round of political poker. But whether Mr Clegg has revealed his ace or yesterday overplayed his hand remains to be seen.