Yes as DaveReidUK explains, 23 was the Landing runway due to the strong Crosswinds and Gales blowing usually from the South.
23 was used when the mean cross wind component on the main runways exceeded 25kts.
Configuration would be 28R for departures and 28L/23 for arrivals.
Pilots indicating which one they wanted on first contact with Approach.
Radar to visual or surveillance radar approaches only to 23. No ILS.
It was, I gather, a real pain to use from an ATC point of view.
Horrendous taxi routes and lots of runway crossings on the ground.
Strange vectoring, SRA's, usually always in nasty weather with Gales, and strong winds that would make it fun on the Approach side coming in over the Gas Holder.
I had many Jump Seat landings on to 23.
Never ever remember seeing anything big Take Off on 23 except a Brymon Dash -7.
The reciprocal RWY 05 was IIRC OOU, before much of my time working at LHR.
Terminal 4's Stand expansions was the catalyst in RWY 23 closing.
It was much used as a taxi-way when not in use as a Runway.