I believe the green "LH" beacon, located on Beacon Road, south of the old intersection between 05R and 33L, has long gone. One of the past DCATCOs at Heathrow always used to ask about it during Aerodrome validation boards... "You've driven round the airfield?".. "Yes".... did you notice anything particular on the southside?".. "Er.... the green beacon flashing LH?" "Ah yes.... very good". Tick!