I wonder if the manoeuvre would be regarded as illegal in the States.
FAR Section. 91.119 Minimum safe altitudes: General.
(a) Anywhere.
An altitude allowing, if a power unit fails, an emergency landing without undue hazard to persons or property on the surface.
(b) Over congested areas.
N/A
(c) Over other than congested areas.
An altitude of 500 feet above the surface, except over open water or sparsely populated areas. In those cases, the aircraft may not be operated closer than 500 feet to any person, vessel, vehicle, or structure.
(d) Helicopters.
Helicopters may be operated at less than the minimums prescribed in paragraph (b) or (c) of this section if the operation is conducted without hazard to persons or property on the surface.
I also wonder why some people think it's hazardous to people on the bridge to fly a helicopter through a gap 100' high x quarter of a mile wide.
We Brits are well known for complying with rules, whether in aviation or otherwise. Might it be that we fall into the trap of subconsciously assuming illegal = dangerous?
Or that, if something is safe, the CAA would allow it and, if it's forbidden it must be dangerous?