I think that NR Fairy is correct in suggesting that 750ft alt around the Millenium Eye is not legal. And as far as I can see, it would not be legal under any of the proposed change options either.
The Eye is (just) outside the London Heathrow Zone (Cat A) but inside the City Zone (Cat D Airspace). Inside the Heathrow Zone any ATC clearance on the routes will be SVFR, which gives an automatic exemption from the 1,500 ft rule. So, inside the Heathrow Zone the 500 ft rule and landing safely in the event of an engine failure are the main low flying concerns. In the City Zone, you need to be a bit careful. At the "standard altitude" on H4 of 2,000ft you should be OK, but be careful of any reduction from this. Thames Radar often offers clearances such as "hold at London Bridge at 1,000ft". If this is a VFR clearance which it will be during the day, the helicopter will inevitably break the 1,500 ft rule. I have tried to raise this in discussions with London Area ATCers but it seems to fall into the "too difficult category". Even the standard "at 1,500 ft" clearance for direct tracks through the City zone for twin engine heles would probably involve a breach of the 1,500 ft rule, since there are lots of (fairly) tall buildings in that area.
Just hope they do not find a 1,500 ft measuring tape!
There was a similar problem a while back as you leave the Heathrow Zone at Bagshot on H3. This inevitably involves flying over congested areas. A well known and regarded pilot was threatened with prosecution for breaking the 1,500 ft rule just outside the zone. Within the zone there is a SVFR clearance, so no need to follow the 1,500 ft rule. However, the max alt allowed on that route at the zone boundary is 1,500 ft. This forces you to fly at or below 1,500 ft at the zone boundary. When you step 1 inch outside the boundary you must then instantaneously increase your altitude by several hundred feet.
Some resident NIMBY complained to the CAA about overflying, they presumably looked at the radar traces and hey-presto case proven.
In the end, the prosecution was dropped after lots of industry pressure was applied but you have been warned. Common sense is a fairly rare commodity.
