) gurgled happily, sounding much like they were
saying :

Although between Chalfont & Latimer and Chesham its the longest gap
between two stations. And the shortest I think is between Herons
Quays and Canary Wharf.

But I thought that Leicester Square-Covent Garden was the shortest
distance between two stations on London's rail transport network.

Shortest street distance, p'raps.
Shortest line distance may well be on the DLR.