Michael R N Dolbear wrote:
I would also like to know if a similar sleeper (or just overnight on a
sleeper train) ticket which continued across London (Maltese Cross
symbol) would have the same problem on LU or NR.

Any ticket where you can't complete the journey by the last train is valid
as long as you restart your journey before noon. So a ticket from Woking to
Welwyn would be valid on the morning tube if you happened to start your
journey on the last train.

Whether staff will accept this is another question...

Theo