London to Strasbourg by train

The Eurostar will arrive in Paris at the Gare Du Nord, but the train on to Strasbourg will depart from the Gare de l'Est.
This guide explains how to make the transfer between the two stations.

When making a a booking, check the connection time between the arrival at Gare Du Nord and the departure from Gare de l'Est.
Due to the more limited number of connections available many of the end-to-end options currently allow more two hours between trains, so if the Eurostar arrives on time an option will be to have something to eat/drink in a brasserie by the gare de l'Est.

Or you can avoid having to making to make your own way between these two stations in Paris, if you opt to take the alternative route via Lille.

Book Early And Save: Yes

Online bookings open: 90 days ahead

The very cheapest tickets tend to sell out particularly quickly on this route; they're more likely to be available if you can travel on a Tuesday - Thursday, or are happy to set off from London early in the morning.

The price below is for a one way fare, if you're booking a return ticket, it's likely you will be offered a cheaper price in each direction.

In the unlikely event of the Eurostar arriving too late in Paris to make the booked connection, tickets can be transferred free of charge to a subsequent departure on to Strasbourg.

A big plus of booking the Eurostar direct on Eurostar.com is that you can access a 'Manage Your Booking' facility - which enables you to change the seat that you will have been initially assigned when making a booking.
Click on the 'train details' for more information.

The different types of ticket summarised

Also worth knowing is that when travelling by Eurostar you can choose between three classes of service, and this also impacts on the exchanges and refunds of what Eurostar refers to as 'Flexible tickets'

If you book Standard or Standard Premier tickets, you can exchange them if need be, to an alternative departure on your booked route; but if you want to transfer your ticket to a new departure less than 7 days before your travel date, you will need to pay an admin fee of £30 for Standard Class tickets, £40 for Standard Premier tickets PLUS the price difference with the new ticket you will be booking.
What's new, in response to the pandemic, is that these £30/40 charges aren't applied if you want to transfer to an alternative departure more than seven days before your travel date.

Business Premier tickets are less restrictive, in response to the pandemic they can now be refunded and they can be exchanged to alternative departures without paying the admin fee, or the price difference.

Eurostar's full ticket terms and conditions are here

Using Rail Passes on Eurostar:

Rail pass users can now pay reservation fees to travel on Eurostar trains, in a similar manner to other international European high speed trains.

The new rail pass reservation fees are similar to the cheapest single journey ticket prices, but as those cheapest tickets can sell out quickly, it's likely that the rail pass reservation fees will save money.

You can purchase these online with no booking fees via B-Europe - or they ARE now available on the Eurostar website.
Booking in advance is recommended as it's not unknown for rail pass reservations on Eurostar services to sell out days or weeks in advance, there is evidently limited availability per departure.

You can obtain a rail pass reservations without paying a booking fee at Eurostar stations.
However, if you want to do this on the day of travel be prepared to be flexible re: the train you will take.

If you are a UK resident, your rail pass + reservation is only valid if you take a train from the UK on the first day that your pass is valid for and return to the UK on the final day that you will be using a pass.

Making the connection between the Eurostar from London and the TGV to Strasbourg at Lille Europe has the major advantage of avoiding the need to between stations in Paris.

You'll need to make your own way from the Gare Du Nord to the Gare de l'Est if you opt to take the alternative route via Paris

The train which typically departs London at 11:04 daily usually has a conveniently timed 36 minute connection into a train on to Strasbourg, hence this option is usually available for booking as an end-to-end journey by the ticket agents.
However, because the transfer time in Lille, when taking the 15:04 from London is more than 90 minutes, this combination of trains can require the booking separate tickets for each part of the journey.

Book Early And Save: Yes

Online bookings open: 90 days ahead

The search results for the London to Strasbourg journeys on the these ticket agents, combine this journey via Lille with the alternative connections via Paris.

The connections via Lille are from the trains which typically depart from St Pancras International at 11:04 and 15:04.