In an ideal world, Heathrow would have six runways, cunningly arranged in pairs, at 60° to each other, so that aircraft could land and take off in any wind conditions.
I can't understand why nobody has ever though of that.
Heathrow did originally have 3 sets of parallels if I remember correctly. Lack of space and the need for terminal expansions over the years saw the closures of those runways deemed surpuflous.