Those of you who travel by rail in Britain are familiar with Eurostar, a rail system owned by Britain, France, and Belgium. Lady Fretwell who championed for the Pet Scheme (allowing pet owners to prepare in advance to bring their pets to Britain thus avoiding quarantine at entry) has taken on the fight to allow pets on board. As stated in TheMoveChannel.com, “Lady Fretwell described the situation as “ludicrous” especially as people and their pets are allowed to travel on trains across the Continent and dog owners in Britain are free to take their pets on the Tube and on regional railways.”
Find more about Eurostar’s pet policy here: https://help.eurostar.com/faq/us-en/question/Can-I-take-my-pet-on-Eurostar
Update: Eurostar currently does not permit pets with the exception of guide or assistance animals. Eurostar does not accept emotional support animals.
For information on pet friendly trains in the EU.