I suspect that not many people know that there's a non-TfL bus service
across the Thames at the Dartford bridge/tunnel which links the eastern ends
of the routes on which TfL's 'All London Bus Pass' is valid (372 to Lakeside
on the north side and 492 to Bluewater on the south side). TfL information
offices seem to be unaware of the route X80, operated by Ensign
(www.ensign.com and www.routeX80.com ) since at least 16 Oct. 2004, and it
is not (yet?) shown on either London Buses' SE London bus map or the
National Rail London Connections rail map, BTW it also links various rail
stations, notably Chafford Hundred and Greenhithe, but all are outside Zone
6. IMHO the view from Dartford bridge (southbound only) alone is worth the
fare ;-)

Regards,

- Alan (in Brussels)