What was the sting in the tale re the fare
I suspect the fare was exactly the same as if they'd done a full TransAtlantic voyage - or in this case, the full Round Britain voyage, but the principle is the same.
That was done in case they couldn't sell the space on to someone for the Cherbourg - New York ( or vice-versa ) leg; Eric Flounders explained that to me once a bit over 40 years ago when I enquired about doing just the Channel hop to "claim" a ride on QE2.