The street distance between the station entrances of West Brompton and Earl’s Court is just 461 m, shorter than a lot of OSIs in Central London. If I measure platform to platform, it is 740 m which takes about 9 to 12 minutes to walk between them. If I get off an eastbound District line train at Earl’s Court and head straight to the rear exit, while a companion goes to the platform of the opposite direction and wait for a train (which can take up to 5 minutes or even worse as the District line is notorious), I would have already entering the station at West Brompton by the time he gets on a train to Wimbledon.