Today I caught the 2045 (Actually 2046) Thameslink service from London St Pancras to London Bridge (9J61), which was delayed because it was stuck behind the late running 2035 service, which actually left St Pancras at 2044 (9R55) At London Bridge 9J61 sat at a red signal outside the station for a couple minutes, then as I saw on opentraintimes the route was set to Platform 3 (it was booked for 4) as 9R55 was occupying platform 4 for a while (13 mins according to RTT). I saw the route was set at around at 21:03:30ish and it arrived London Bridge at platform 3 at 21:04, I got off the train and lots of people were running up the stairs. While this crowd was halfway up the stairs, the door hustle alarm sounded. People heard the alarms and a stampede happened up the stairs and escalators and a few people slipped through the doors as they were closing. At 20:04:45 the doors shut. The train left at 20:05:00 (I'm not sure if platform staff dispatched it or the driver does it themselves at London Bridge) Anyway about 40-50 people missed 9R55 and had to wait 30 minutes for the next Horsham service. The platform staff got shouted at by a lot of angry people saying "why did you let it go" etc. 9R55 was 5L and I can understand it was priority to let it go to try and get back to time (and it arrived RT at Horsham) Should trains wait and extend their dwell time if there is a platform alteration? 1 minute 15 seconds from the announcement to change platforms at London Bridge is next to impossible, and if you are disabled you have no chance (getting two lifts). Thoughts?