Heading wildly off topic here, but the yellow flowers around Ockham are probably rape (strange name). I know, because I am strongly allergic to the pollen
. The seeds are used to make vegetable oil.
Back on topic,
I don't have a current flight guide to hand, but looking in my '96 Pooleys there is a mention of maximum altitude in the ATZ of 800 ft when Heathrow Rwy 05 is in use for Landings or Rwy 23 for take-offs. I never noticed that before, but then it is a rare event at Heathrow. Presumably Fairoaks R/T would inform you if that was the case.
TG