Starting any new train service is like running a marathon. Starting a sleeper is like running a marathon in a Winnie-the-Pooh outfit. Starting a sleeper *from London* is like running a marathon in a Winnie-the-Pooh outfit in 30 degree heat whilst juggling fire & playing the piano https://twitter.com/jonworth/status/1381150279874314241

Requires new bespoke rolling stock with special fire suppression, minimum train length 375m, border controls & security checks at all boarding stations, with secure platforms & stabling. Sleeper economics already more difficult than day trains, this pushes it right over the edge.

So unless something major changes (and I mean major, like airlines grounded or forced to pay tax on their fuel, security requirements for Channel Tunnel removed & passports checks on arrival), Jon is spot on in explaining the way to go.

And all of *that* is eminently possible...