How to take the rail journey from London to Torino/Turin

The route taken by the Paris to Torino / Turin trains has been closed until summer 2024, due to damage caused by a landslide.
Replacement bus services have not been made available for international journeys along the closed section of the route.
The alternative route, which is currently the only option, involves travelling via Switzerland and Milano, with at least three connections and a journey time of more than 12 hours.

It is in effect the options 3 and 4 of a London to Milano journey + the journey by train from Milano to Torino / Turin.

At St Pancras:

This end-to-end journey typically involves departing London on Monday to Friday at 08:01 and at 10:31 daily.

Eurostar is currently suggesting that Standard Class And Standard Premier ticket holders should be at the Eurostar departure area in St Pancras International 90 mins before departure; and that Business Premier ticket holders should be there 45-60mins prior to departure.

The departure gates will close 30 mins prior to departure for Standard Class And Standard Premier ticket holders; and 15 mins prior to departure for Business Premier ticket holders.

Our guide to taking a Eurostar from London is here.

Note that London is in a different time zone to mainland Europe, it is one hour behind; hence what can seem like a discrepancy between the journey time and the interval between the departure and arrival times.

Departing from the Gare De Lyon

The Eurostar will arrive in Paris at the Gare Du Nord, but the trains on to Torino will depart from the Gare De Lyon.

This guide explains how to make the transfer between the two stations by RER train.

Though when booking end-2-end tickets for this journey to Torino / Turin, the timetable will allow more than 1hr 15mins to cross Paris from one station to the other.

Making that transfer across Paris by RER train won't usually take more than 30 mins and you won't have to 'check-in' for the Torino train.

Online bookings open: around 4 months ahead

An option is to split the booking into London to Paris and Paris to Torino journeys, so that you will have more than three hours to make a leisurely transfer across Paris - though doing so will likely be more expensive.

Seat reservations are automatically included when booking tickets for both trains.

Your ticket will not include the RER train across Paris from the Gare Du Nord to the Gare De Lyon.

Eurostar train's general ticket terms:

'Customers can exchange tickets for travel in Standard and Standard Premier class multiple times without paying an exchange fee, as long as tickets are exchanged 7 days or more before the departure time of their individual journey
Though if the new ticket option is more expensive the difference in price will need to be paid, but if it is cheaper the price difference won't be refunded.
But make the exchange within 7 days of the individual journey and an admin fee of £30 will need to be paid, along with the price difference
Tickets to travel in Standard and Standard Premier class are not refundable.
In contrast tickets to travel in Business Premier Class can 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 .

Making the connection in Paris:

There is relatively new E.U. legislation which protects travellers against financial loss in the event of missed connections due to train delays, but it only applies to 'through tickets'.
The Eurostar terms and conditions specifically state that when booking journeys which combine Eurostar + Eurostar Thalys trains 'through tickets' will be issued.
'However, 'for all other journeys that combine a Eurostar Service and a service provided by another carrier (such as the TGV or Frecce train on from Paris) including when purchased in a single commercial transaction, those tickets will be separate contracts and issues regarding delays, missed connections, cancellations, compensation, and the management of aftersales will be handled accordingly'.

But SNCF, which operates the TGV train, and Trenitalia, which operates the Frecce train, have signed up to Agreement on Journey Continuation (AJC) policy for when a traveller holds separate transport 'contracts' for an end-to-end journey involving more than one train.
So this agreement applies both when 'a bundle' of tickets / contracts is issued as the result of a single transaction - and if travellers have bought several different tickets for their journey, even from different sales channels/ticket providers.
As long as the passenger had planned enough connecting time to change trains (called “reasonable connecting time”), the AJC will apply.

So in usual* circumstances, if a delay to a Eurostar has caused a booked connection on to Torino to be missed, replacement tickets/reservations should be issued at the Gare De Lyon.
*= But that new E.U legislation specifically states that in exceptional circumstances, the train operators do not need to issue replacement tickets - and the terms and conditions on the SNCF Connect website reiterate this.
These exceptional circumstances specifically stated in Regulation (EU) 2021/782 of the European Parliament include:

• extraordinary circumstances not connected with the operation of the railway, such as extreme weather conditions, major natural disasters or major public health crises...
• ...the behaviour of a third party... such as persons on the track, cable theft, on-board emergencies, law enforcement activities or sabotage.