Not too sure what you are seeing there - 98% of the inbound traffic to LGW is vectored to the south of the field where the two holds 'Willo' and 'Timba' are, and off these holds the traffic is turned Eastbound, normally south of the field. You might just be seeing traffic inbound to LHR routing to the Biggin Hill hold, in which case it would probably be about 8-9000'? Maybe a Director person could chip in here? I don't remember ever being routed north of LGW from the south, although I have occasionally 'squeezed' such from a kind controller on a northern arrival.