On 09/05/2021 17:44, Brian Gaff (Sofa) wrote:
Maybe they were avoiding very built up areas?
Helicopters seem to do that around here, or they fly up following the
Thames.

Aircraft flying over built-up areas are required to be able to land
clear of the area in the case of engine failure. Helicopters can't glide
very far if their engines fail, hence the helicopter route through
London is along the Thames. Police helicopters operate under special rules.


--
Colin Bignell