I'm also local to EGNT and I suspect that on the 'calmer' days, where the westerlies aren't prevailing, the predominant wind is a sea breeze.
I've quite often travelled out early morning/back in the evening and it's very rare to use 07 in the morning but seems a lot more likely in the afternoon/evening, which would back this theory up as the sea breeze will become stronger as the day goes on and the land mass warms up.