Andy,
Article 2.1.3 specifical addresses PFLs and states that several states routinely allowflights below 500' for engine failure training, France allows flight down to 170'.
Annex A 5.3 states that an aircraft will not be allowed to land within 1000m of a gathering of 1000 people without written permission of the CAA.
At North Weald, we have the world's biggest market on a saturday morning, so I hope that some sort of blanket exemption will be allowed, otherwise the CAA Permission Granting Department will be on overtime
Otherwise, I like the 1000' overflight height - in my local area we have towns at 300', + 1500 clearance =1800'. London TMA is at 2500' so we only have 700 feet to play with. OK, so I can always try and avoid direct overflight, but any increase has to be a good thing.