Its getting close to the stage where any further expansion of stands at LTN will be negated by the limited taxiway layout and lack of dual taxiways on areas such as the East Apron
Probably why new taxiway Foxtrot which will run parallel to taxiway Delta has been bought forward to phase 2 with a start date in 2 years time. The new taxiway will have 2 connections to taxiway Delta and 1 connection to taxiway Alpha.