Robin wrote:

I realised today that I don't know which stop is now used at
Stratford for replacement buses when the NLL is not running. I then
found that I can't even find the information online. Manifestly it
doesn't matter as much at most staions as it does at Stratford with
the 2 bus stations. But is there a bit of the TfL, National Rail or
other site(s) which carry this information for TfL serrvices and/or
more generally pl?

It is usually shown on the relevant station page on the National Rail
site. For Stratford it says stop M on Angel Road.

http://www.nationalrail.co.uk/stations/SRA/details.html

Peter Smyth