I lived in Hayes as a kid, and 23 (was it 24 then, or were they just called No 1, No. 6 etc? (but I digress)) was used whenever the rainy south westerlies blew. This brought traffic across the back of my house, and across the Southall gasholder. That gasholder had a big LH painted on it, to avoid confusion with the Ruislip one that had a big N for Northolt.
The country lore for us suburban kids was that if you could smell the coffee from Nestles it was going to rain, and if the planes were landing across us it was prpbably raining already.