RPL has now published a statement about its land ownership and relationship to Sustrans (actually, RPL and Sustrans are entirely different charities). See here:
Future Plans – the composition of our land
More interesting to the average RR member will be the new interactive maps, which show RPL’s land holdings around the country – and inter-connecting routes developed by our partners such as Sustrans and myriad local authorities.
Click here for interactive map at https://www.arcgis.com/home/webmap/viewer.html
These maps could prove useful to RR’s area organisers and walk organisers because they enable users to identify both publicly accessible lengths of old railway and non-railway connections (bridleways, river/canal paths, quiet lanes, etc.) which can be used to link them together.