Travellers face hours of misery after Eurostar cancellations (Getty) / Getty

Simon Calder answers the essential questions facing those wanting to travel through the Chunnel

In the 20 years and two months since the Channel Tunnel opened, there have been four fires on trucks being carried through the tunnel. The latest involved a UK-bound truck at around noon on Saturday, and caused the closure of the link and a frustrating journey for many thousands of travellers.

Q. Just a reminder of the different transport operators that use the Channel Tunnel?

A. Eurostar is the passenger train operation, which runs from London St Pancras to Paris and Brussels. But the tunnel between Folkestone in Kent and Calais on the north coast of France is owned by Eurotunnel, which also runs car and truck shuttles through the tunnel. It was one of these shuttles that had the problem, when a truck being transported from France to Britain was, in the words of Eurotunnel, “smouldering and generating large amounts of heat”. That train was stopped and the truck drivers evacuated; Eurotunnel stopped shuttling, and Eurostar trains were sent back to the stations where they started: Paris, Brussels and London.

The Channel Tunnel comprises a north-going tunnel and a south-going tunnel, with an emergency corridor between them. The fire was in the north-going tunnel. Overnight Eurotunnel plans to run services using the other tunnel, though it’s a sclerotic business - a single-track line is a lot less than half as efficient as a twin-track railway.

Q. How many people have been affected in total?

A. A few thousand drivers of cars and trucks have been slowed down - they didn’t get the smooth 35-minute transfer beneath the Channel that they were expecting, but they did get put on ferries. Eurotunnel has its own ferry firm, MyFerryLink, with plenty of room. It’s Eurostar passengers who are in the biggest pickle, because the cross-Channel train company carries the majority of people between London, Paris and Brussels - and all 26 trains from noon onwards were cancelled -  which Eurostar estimates amounts to around 12,000 passengers.

Q. Why didn’t Eurostar start again overnight?

A. Its operation is extremely complex and depends, among other things, on meshing in with domestic trains in France and Britain. It also has staff rosters than assume a daytime service, so it would be very difficult to choreograph the crews - particularly as so many of them ended up in the wrong places as a result of the closure.

Q. What are the options for stranded passengers?

A. In the short term: for passengers unable to reach their destination, Eurostar is offering a hotel stay up to £150 per room per night and up to £50 per person on meals. (That’s pretty generous, considering the closure wasn’t the fault of Eurostar - and many of the passengers were taking advantage of special January fares of under £30 each way.) The company says its staff have been handing out leaflets with all of this information to customers in stations. Some passengers who had pressing reasons to travel paid over £300 for a one-way flight from Heathrow to the French capital, but most of them will be trying to reschedule on sunday or cancelling the whole trip - especially if it was just a quick weekend away.

Q. For Eurostar passengers who are determined to get to their destinations - is it just a matter of turning up at the station and hoping for the best?

A. No. Eurostar plans a full service on Sunday, but priority goes to people who are booked on Sunday’s departures rather than the frustrated passengers from today. Eurostar is telling them not to turn up at the station, but instead to call the contact centre on 03432 186186 from 8am on Sunday, with a view to getting re-booked on a train leaving some time after noon.