The departure lounge of Eurostar at St Pancras has a couple of racks of free postcards commemorating 20 years of Eurostar. There are eleven postcards and a reply card asking for comments/thoughts on the impact of Eurostar to cross border logistics/relations. The cards are not obviously available at Brussels Midi or Paris Nord.
Click here to see the postcards:
There is set of cards available to the first member who asks ( postage £1).