If anyone has pointed this out already, I apologise!
Getting to Elstree from Central London is not comparable with getting to Kings Cross, is it? Same at the other end; NCL is a long way out of town.
In his letter Tom revealed that if he had taken the train from London King's Cross at the 17:00 it would have arrived at 19:42.
Instead, the flight which departed at the same time from Elstree Aerodrome, near Watford, London arrived at 18:30. Nearly twice as fast.
That "nearly twice as fast" is pretty stupid.