What sort of savings will I make?

This is where Snap delivers: the savings are fairly good. When The Telegraph checked all available prices, on the London to Paris routes, the Snap tickets (returning after two nights) averaged at £123.13, which is 52.8 per cent cheaper than the cheapest scheduled return Eurostar tickets. One-way tickets to Amsterdam averaged at £57.22, 60 per cent cheaper than usual, and the Brussels return tickets averaged £113.13, which is 50 per cent cheaper than the scheduled returns. 

However, the savings are not as cheap as in the 2016-2017 iteration of the scheme, when tickets started from just £25 each way.

Is Snap cheaper than flying?

Yes, but only marginally. When we compared the cost of Snap return tickets (returning two days after the outbound journey) with the cheapest direct flights listed on Skyscanner on those same dates, we found Eurostar Snap was £10.60 cheaper than flying to Paris and £24.40 cheaper than flying to Brussels. Getting a single Snap ticket to Amsterdam is on average £14.91 cheaper than catching the best-value available flight.

Of course you also need to factor in the cost of travel to the airport, although this becomes a moot point if you live outside London, as you’d have to travel into town to reach Eurostar’s terminal at London St Pancras anyway.