Yes, think I understand now the blend of SVFR and IFR that's being used by choppers within the Heathrow Zone. As F/W GA of course, SVFR is pretty much you're only option and that's only around the fringes or the BUR-Ascot transit.
Am working in the area of infringements, so was interested to hear what would constitute an infringement in terms of the heli-routes, if SVFR. How far off track do you have to be to be considered effectively "in the zone"??