Talks on the formation of the next government have ended for the day with Conservative and Liberal Democrat officials declining to say whether a power-sharing deal has been agreed.
Minutes after Gordon Brown had announced his resignation as Prime Minister, negotiators left the Cabinet Office.
They had been holed up there for the afternoon trying to come to an agreement on the "specifics" of a coalition government.
"We have completed our discussions in a good atmosphere and are now returning to report back to Nick Clegg and our parliamentary colleagues," Lib Dem negotiator Danny Alexander told reporters.
Conservative negotiator William Hague said he would take back recommendations to his colleagues.
A crowd of journalists, tourists and bystanders had swelled outside the building where the talks had been taking place.
Anti-war protesters have been demonstrating, unveiling a large banner that read "Troops Out Now" along one wall of the building.
Some shouted "Fair Votes Now" and "No Deal Without PR" in a reference to Proportional Representation, which the Lib Dems have been desperate to achieve in any deal.