text: Fixed the SE end of the platform from the lengths and angles of the route from the lift, then found this matches a slightly wider feature showing on OS OpenData Streetview, so the platform should be pretty good now.  Estimated the more southern escalator + subway route lengths and angles and hence the underground ticket office.  Didn't walk the escalators+stairs+footway to the middle of the platform, although it can be accessed without a ticket via the lift and platform...