You can run London to Europe via HS1 and tunnel, but the operating costs are insane. Anybody who propose that would get shut down by the „rail bubble“ extremely hard (like midnight trains did a couple years back). I think it would be nice, but it’s far off.

As for intra-UK sleeper: yes there are some possible routes, but the market is small. Developing custom trains for that would be very expensive. And the concepts we propose don’t work well cut the profile is so small.

This was true a few years ago, but today the regulatory environment is very positive for these kind of services. You will see many non-eurostar open access operators on those tracks within the next year or two.

I wouldn't massively bother with intra-uk yet, I agree wholeheartedly.