It looks to me that in this case it is for airspace containment purposes; the granted CTA's to EGLF would be as small as feasible, consistent with the purpose that the CAS is in place for in the first place. This reduces the impact on nearby aerodromes/aviation users.
The FAF being at the points where they are ensure that aircraft on the ILS will remain 500ft above the base of CAS of the various stepped down airspaces, whilst following the ILS profile down into the CTR.
Not obviously related to obstacles, as EGLF SMAC chart still has lower levels available (in theory), say if one was arriving/transitting IFR from outside CAS.
Last edited by Red Four; 26th Oct 2020 at 19:40.
Reason: grammar