I've received notification from Network Rail that they plan to put a 15m monopole mast on the stretch of line between Foxborough Gardens and Prendergast Ladywell Fields (formerly Crofton School).
The letter says that the mast is part of plans by Network Rail to "rollout a nationwide Railways Communications System across the entire network" and that this new radio system will for the very first time, allow direct and continuous communication between train drivers and signallers which will improve safety, reliability and punctuality on the rail network".
The letter says that they are aware that the construction of any mast may be of concern to residents who live nearby and that they plan to notify those residents before construction takes place, with information on the new system and a 24-hour helpline for any questions or queries. It also says that they are in discussion with Lewisham's Planning Department, but that they believe the mast falls within their permitted development rights to maintain and ensure the safe operation of the railway.
As far as I can tell from the map, the nearest homes to the proposed site are in Sinclair Place (just off Manwood Road) and the homes in Foxborough Gardens that back onto the railway line.
I don't have any more information about the type of mast being proposed or what the potential risks are, but I thought I should flag it up to readers, as I know that those concerned about the proliferation of mobile masts recently (eg of the Ladywell water tower in nearby Dressington Avenue) may want to be informed.