I thought the problem was the temperature difference between the outside and the tunnel

It sounds like they're making up excuses as they go along. Wonder what excuse they'll concoct for leaving people stuck in unheated trains for hours on end, instead of rescuing them, and leaving stranded customers on the wrong side of the channel, instead of laying on alternative transport.

It did say on the lunchtime news that the ferries are running fine, and thy have room for passengers. So, surely Eurostar could transfer the poor people on to them.Some people have been stranded since Saturday,it must be dire for them.

It's a good headline as it harks back to the days of British Rail complaining about points failure due to the wrong type of snow.  However, the chief executive has just been on Radio 4 explaining what actually happened in simplistic terms.  Sounds to me like snow dust got through gaps in the metalwork and caused condensation somewhere in the electronics when the humidity changed rapidly from outside to in the tunnel..

Actually, the "wrong kind of snow" story was essentially a very similar problem. Very fine snow was being sucked-in through an air intake, and when it melted it shorted-out some of the electrics. It was a genuine design flaw, but BR's PR people hadn't really thought how silly blaming the snow would sound to the GBP...

we had massive fluffly snow today, it was beautiful

By coincidence I have been on the Eurostar. It's great!

Have they never had snow since it was built?....