TfL have published an Options Assessment Report for the Bakerloo line extension that considers the feedback of the 2104 public consultation including alternative routes proposed by the public.
The upshot for Beckenham is that whilst an extending the Bakerloo to Beckenham and Hayes has not been ruled out it will not proceed in the immediate future. TfL need to work out the impact of converting the Hayes railway line into the Bakerloo and whether doing this best meets rail demands for this part of the Borough in the future and the capacity for housing/commercial development along any Bakerloo extension to Beckenham, West Wickham and Hayes to fund the extension. The latter was a significant concern for local people that were opposed to the extension.
TfL propose that phase 1 will be extending the Bakerloo from Elephant and Castle to Lewisham via the Old Kent Road. Having 2 branches to Lewisham via the Old Kent Road and via Camberwell was ruled out, however TfL are investigating the possibility of re-opening the Camberwell Thameslink Station.
You can read the Options Assessment Report for the Bakerloo line extension online at tfl.gov.uk/bakerloo-extension.