Heli1, thanks for that. Yea, I think you are correct about it being a N-Reg machine. The problem I have is that, I think Hughes built a non-flying mock-up of the Hughes 500 in the exact same colour scheme as this flying example. It actually looks like this machine was converted from an OH-6A but has a civilian column-style instrument panel. It might be the early demonstrator that was then painted in a blue-and-white scheme and featured in a lot of Hughes publicity material from the late sixties. Thanks anyway.
500 Fan.