Originally Posted by
Luther.e
If arrival at E and D departure (most likely), shuttle train to D and security when you get off the train. No passport checks.
If arriving and departing from the same area then no security or passport checks just walk to next gate. Note that buses will drop you at D if you arrive at a remote stand.
South Africa is not a secure arrival country. If LHR departs from E, pax will be subject to transfer security in E.