Southern Railways are introducing a new reduced weekday timetable from Monday 22nd February until further notice.
From Forest Hill/Honor Oak Park the morning and evening peak services that have been operating twice an hour between Crystal Palace and London Bridge via Sydenham and v.v. will no longer operate leaving 2 trains an hour throughout the day between London Bridge and East Croydon and v.v. calling at all stations.
For full details of all changes see Southern - Revised-timetable
Southern are also advising passengers to ensure they check every journey before travel, as some overnight and weekend engineering works may not show in Journey Planners until one week beforehand.