Passengers left stranded by the Eurostar snow saga reacted with anger today as rail bosses resumed services - but told them they were still not guaranteed to get home for Christmas.
Travellers queued in their thousands to board the first journeys out of St Pancras International after three days of cancellations.
Amid chaotic scenes at the station, some spoke of their frustration that they were not guaranteed a seat, saying bosses still had "a lot to answer for".
The first batch of trains left the station as planned and services would operate on a "shuttle basis" to get as many people across the Channel as possible, a Eurostar spokeswoman said.
But when asked whether ticket-holders were guaranteed to get home in time for December 25, she said: "I cannot guarantee that, no."
Marc Stevens, 39, his wife and 18-month-old daughter were among thousands stuck after havoc was caused when snow got into the electrics of a number of trains.
Mr Stevens, an IT worker from Reading, Berkshire, who was due to travel to Paris on Saturday, said: "We are travelling with a young child yet we are not assured of a seat. It's been an appalling few days as we have missed out on seeing relatives who we had never met our daughter. We just want to go now."
Cedric Berger, 31, from Clapham, south London, was also due to travel back to Paris to see his family on Saturday.
"It's been annoying but I have been told I'm definitely getting on. It's the people that were going to travel today or tomorrow that might miss out on Christmas."
Mother-of-four Gisele Bulembi was in a particular rush to travel to visit her sister, who had broken both her legs.
Herding her children and Christmas presents through the queues, she also revealed that she was carrying a turkey to cook on December 25.
The 35-year-old, from Hackney, east London, said: "My sister lives in Brussels but she recently broke both legs and cannot do any cooking.
"It's difficult enough carrying all this stuff. The fact we might not even get a train just makes things worse."
Angeliki Pollato and Bryan Field, who were travelling to Italy for Christmas, said rail bosses should have been prepared for the big chill.
American Mr Field, 33, a physics professor at Durham University, said: "It's amazing how a little bit of snow causes complete breakdown.
"Why aren't the British prepared? We have lost £200 to £300 now in hotel fees. I hope we will be reimbursed."
Daniel Sharp, 29, from Finsbury Park, north London, was forced to postpone his weekend plans to visit his girlfriend in southern France.
Before boarding the 7.30am train across the Channel, he said: "I'm glad to be getting across to see her at last, but am highly unsure that I will now be getting back to Britain for Christmas.
"They definitely have a lot to answer for."
Amid a police presence, scenes remained calm as queues stretched the length of the station.
Matthias Maher, a Eurostar official, had the unenviable task of telling fed-up passengers they were not guaranteed to travel - despite turning up at the railway station in the early hours.
On average, 15,000 people travel from St Pancras each day.
"We are looking at running extra trains," said Mr Maher. "But it is very much dependent on the weather.
"There is just no way of guaranteeing seats for the people here. That's a difficult thing."
John Mitchell, 42, and his family, from Balham, south London, were among those told they may be turned away.
Travelling with his two sons and wife, Fabienne, he said: "We are not guaranteed but we are staying confident. I have been told there will probably be nine trains so I am hopeful we will be with family in Paris by tonight."
More than 2,000 passengers were trapped on trains overnight in the Channel Tunnel on Friday.
A limited service was resuming for passengers who had tickets for December 19 and 20, and was then working through remaining ticket holders over the next few days.
Eurostar chief executive Richard Brown said he was "very, very sorry" about the breakdowns and that modifications to the trains were being tested.