Polarbear
Established Member
I've just come across this article on Seat 61.com which makes for very pleasant reading; 
http://www.seat61.com/news.htm
Excellent news for me as I shelled out several hundred quid on E* returns last year, as well as a cheeky flight to Zurich! As long as the promised availability is maintained, this can only be a good thing.

http://www.seat61.com/news.htm
Eurostar now accepts InterRail & Eurail passes..!
Eurostar joined the InterRail & Eurail schemes as from 1 January 2017. Previously, they were only associate benefit providers, the benefit being a relatively expensive & pointless passholder fare over £90 that (1) was more expensive than regular fares if you booked well in advance and (2) was usually sold out at short notice so if you wanted one you had to book it well in advance - in which case I refer you back to point (1). The new passholder fares of 30 in standard & 38 in standard premier for 1st class passholders are great value, and I'm assured that they'll be widely available in advance and reasonably well available even o the day of travel, even if not on busy trains. And your pass only needs to be valid in the country where the Eurostar journey starts or ends, so even a Benelux InterRail pass would allow you to buy a London-Brussels Eurostar ticket for 30. This is a huge step forward, and I welcome it with open arms. For more details, see the Eurostar passholder information here.
Excellent news for me as I shelled out several hundred quid on E* returns last year, as well as a cheeky flight to Zurich! As long as the promised availability is maintained, this can only be a good thing.