We were denied boarding / checkin for our train to...

We were denied boarding / checkin for our train to Brussels because we were at the checkin "only" 27 minutes before the trains departure.
Eurostar says 30 minutes is required - OK. We then queued to get our tickets changed - loads of people with the same problem, some said they were there 40 minutes before - still weren't allowed to board.
Eurostar finally charged 30 Pounds per person to get the next train - in our case 2 hours later. While we were waiting we saw the same story happen all over again for an Eurostar to Paris -
around 20 people who were in time for departure not allowed to board and queuing in front of the ticket office.

This would all be understandable if the 30 minutes were an actual requirement. However, passing through security and passport control two hours later
took us not more than 10 minutes, people were boarding the train up to 5 minutes before it left. We could have easily reached our earlier train. Eurostar's boarding policy and its enforcement at St. Pancras is thus clearly a ripoff. 60 Pounds and two hours wasted for pure bureaucracy. Not recommended.