Brexit is coming whether you want it or not!
The big question is whether it will affect the operational railway in terms of Eurostar or freight?
The answer is likely to be yes and yes whether or not there is a deal between the UK and the EU. The extent of the impact, however, will be determined by the type of deal, if any, agreed.
The biggest risk, in railway terms, is if the politicians both here or in the EU play political games. For example if a French Transport Minister decides that France will no longer recognise the train driver licence of a British train driver then many cross border services would come to a stand. This would be despite the requirements for holding a licence being exactly the same in both countries. We believe the risk is small. It certainly would be irrational, however, politics is not necessarily a rational game!