Gnd, you make a valid point but add on another ten feet and there are no 'rules' that I am aware of being broken. If it was over the middle of Winchester or Andover or any other conurbation then fair enough.
We have no idea what the cab was doing- CAD, IP to target etc- so all I am saying is just because it was 'low' does not mean it was doing anything illegal or reckless.