IO540, no I don't have a reference and am not all that certain that one exists. I speak to the folks at Gatwick quite a lot, and sit on a few fairly important committees, so that's my understanding of the latest position from there. It does however seems to be in a constant state of flux.
Best advice I can offer at the moment is that if you have a specific mod in mind, phone the nearest CAA regional office and ask to speak to a "surveyor" for a chat about it.
G