In message , Paul Corfield
writes
there are two routes which are very close to that logic but they do stop
at stops other than Tube Stations. They are the N5 and N20 which cover
the northern branches of the Northern Line to Edgware and Barnet. In one
case the route covers roads not served by daytime buses.

Wasn't one of those actually promoted as "Your Night Time Northern Line"
on special route branding once?
--
Ian Jelf, MITG, Birmingham, UK
Registered "Blue Badge" Tourist Guide for
London & the Heart of England
http://www.bluebadge.demon.co.uk