A Tube strike is still threatening to disrupt the entire network on New Year's Eve, after talks broke down.
Will the Tube be running when Big Ben strikes midnight?
Thousands of London Underground (LU) workers are due to walk out for 24 hours at noon on Saturday.
On Thursday the RMT union refused to attend talks, after LU turned down its request to delay the introduction of new rotas at the centre of the dispute.
London's mayor said the strike would "spoil a great night out for hundreds of thousands of Londoners".
Crowds fill the streets around Trafalgar, Parliament and Leicester squares and the Victoria embankment to hear Big Ben strike and watch the fireworks display at midnight.
The mayor had planned to offer free travel on the Tube from 2345 GMT on New Year's Eve to 0430 GMT the following day.
But now all Tube lines face disruption, because of the row over the implications of shifting LU staff onto a 35-hour week.
The Rail, Maritime and Transport (RMT) union says when it agreed to make the change, it had not been shown new work patterns.
It says it understood 200 staff would be moved to new jobs, but claims there are plans to move up to 800 people - which it says will leave some stations short of staff and compromise safety.
The union had offered to suspend the action, if LU agreed to suspend the introduction of the rotas, to allow more time for talks.
But Tube bosses turned down the "ultimatum", saying it could have compromised holiday arrangements for thousands of staff.
Of the strike, RMT regional organiser Bobby Law told the BBC: "We had no choice really.
"It's LU that won't suspend the introduction of the rosters which we believe is unsafe - not just for our members - should they be introduced. We believe they will be unsafe for the travelling public as well."
LU's chief operating officer, Mike Brown said the union had not raised any specific safety concerns with them.
"Does anyone really expect that, after what we have seen this year where the Underground staff behaved magnificently in the response to 7 July, that we would ever want to operate a system that was less safe?" he said.
He said LU would remain available "for the next 24 hours, right up to the 11th hour before this strike" for talks.
"Striking on New Year's Eve is not about industrial relations," he said.
"It is a cynical way to exploit Londoners and I think it is a big mistake."