Below are some extracts from documents obtained by a member of the Forest Hill Society under the Freedom of Information Act from Transport for London:
Covering letting in response to the FOI request:
"By introducing eight East London Line trains per hour (tph) to the Slow Lines, it is anticipated that the current service to London Bridge will reduce by two tph all day, i.e. from eight tph in the peak and from six tph to four tph off-peak. Thus, the number of trains running on the Slow Lines increases by six tph all day. The final train service specification will be dictated by the outcome of Network Rail’s South London Route Utilisation Strategy which goes out for formal consultation between May 2007 and August 2007."
Letter from Peter Foot (Department for Transport) dated 15 June 2006 to Alison Clarke at Network Rail:
"We understand that Network Rail remains 'uncomfortable' with the intensity of the service foreseen though the combination of ELL and South Central franchise trains. Whilst DfT acknowledges these concerns, the Department is very aware that passenger demand forecasts indicate that the number of passengers using the rail network, particularly in the commuting peaks, will continue to rise for the foreseeable future. This, in turn, is likely to drive the need for more trains to operate on the network. Some of the increased capacity benefits deriving from the introduction of ELL services would be lost if there were to be a significant reduction in South Central franchise service. The level of franchised service has already been reduced in order to arrive at the specification that was agreed on 19/8/05, and it is doubtful whether a lower level of peak direction service is sustainable."
I believe that these two quotes demonstrate:
a) That although a reduction is services by 2 tph is not necessarily the final outcome, it is what is anticipated by TfL.
b) Network Rail may wish to further reduce service through Forest Hill, either by further cuts to existing services or by a reduction in the ELL use of the line. DfT believe that further cuts would negate any benefits derived from the ELL extension.
c) DfT forecast that the current planned capacity will not be sufficient in the foreseeable future (the italics for more were in the original letter not added by me). This means that cutting any services to London Bridge in 2010 will lead to overcrowding in the short term on the route to London Bridge (our projection), and major problems in the medium term as demand increases according to DfT projections.