I have here a ticket purchased from Eurostar, from Rotterdam Centraal to London via Brussels.
For the sections referring to each segment, it says "Your ticket gate closes 30 minutes before departure". This includes the Thalys Rotterdam to Brussels Midi segment.
I'm pretty sure they don't actually have ticket gates at Rotterdam Centraal... what does this actually mean?
I'm guessing it really only applies to the Eurostar portions of the journey.