I spent most of my career based at LHR and can never remember a go around ordered by ATC in fact the only one I do remember is after wishing a captain 'good luck' after he asked for a visual from base leg and was obviously too high! Land afters were more common of course but still not that many ( i never liked them unless a high speed was available and believe that should be mandatory)
LHR was the slickest ATC operation I ever came across, the problems for us always came at other airfields which when they suddenly got busy they couldnt cope with the traffic. I certainly can remember more GAs at other airfields!