LHR has not had the “runway 3” properly known as 23L since the late 1980s. It was not an emergency runway. It was only used when the crosswinds were too high on the main runways. It was extremely short. It only had radar controlled/visual approaches. Also it could not be used in the reverse direction 05R due to buildings on the approach. The outer stands at T4 then took over much of the southerly end. It is still used as a taxiway at the eastern end of Heathrow.