Genghis,
That's the most sensible suggestion that anyone's come up with so far, IMHO.
I started looking through my VFR guide last night, wondering exactly what the situation was. Well...confusion probably covers it. Very, very few airfields weren't PPR, though Southend wasn't, as Keef said. Some said PPR at the top of the page, then qualified it by saying PPR should be by phone, or by radio, or in winter, or similar. Some qualified it by saying PPR was essential, which suggests to me that they know that PPR at the top of the page is usually ignored because it's become part of the background of the guide.
Genghis' suggestion would make sense of the whole thing. And more importantly, it probably means that pilots would take notice and do it!