I think that the question was really aimed at getting some clarity on "in sight of the surface". This is not a limitation of the UK definition of VMC, so much of this thread is misplaced. Rather the concept is a PPL licence limitation removed if you hold either an IMC rating or IR.
So far as I am aware, there is no definition of "in sight of surface" contained within the usual reference sources.
To fulfil the spirit of law you might argue that the "surface" you can "see" should be sufficiently close and sufficiently large that you could glide down onto it without going IMC, should the need arise.
That definition is my own, make of it what you will.
2D