I'm not read-up on the project in detail, but from what I know, it is a very ambitious one: it's not simply about bringing standard European cross-section freight to Britain, but going beyond, as US-style double-stack containers are beyond the largest European normal-gauge cross-section. I consider this part of the project less viable, not only due to significant infrastructure investment needs this side of the Chunnel, but compatibility, too -- e.g. containers travelling say from Warshaw would have to be re-loaded in Paris or Lille.

If they would just go for normal cross-section, and get a good agreement with SNCF for the passage of freight there, I think it would make sense.

I note that in terms of railways out of the local standard, the most striking example is a Russian broad-gauge freight line, which extends 400 km into Poland from the Ukrainian border, with a planned extension (which is unlikely until Poland is ruled by nationalists) reaching the edge of the Czech Republic. (Check this map, it's a narrow red-dotted green line.)

Another negative point from my point of view is going for diesel traction, but financially, it is unfortunately a good choice.

_{*Lunatic*, n.
One whose delusions are out of fashion.}