As an aircrat owner I get a personal copy of the GASIL each issue. In the Current GASIL on page 5 there is a very specific explanation of the IMC and what it allows you to do. It also specifically explains that the IMC unlocks the PPL restriction of flight insite of the surface.
Curious about this whole discussion I called the CAA and they told me that a pilot flying in the UK on any licence was bound by the terms of his licence or by the UK ANO whichever was the most stringent.
I then asked them the question that has been going around this thread and they said that only a pilot with an IMC or an IR could fly out of site of the surface in the UK regardless of where there licence was issues.
Open to comment.