I've just looked at the wording in Pooleys - second hand, I know, but let's hope they've copied this correctly from the scheme details.
"... for genuine emergency or precautionary diversion landings ..."
Well, the first is easy to spot, because the pilot will have called at least PAN, won't he, so what does "precautionary diversion landings" mean? The only other type of "precautionary landing" I've come across is the forced-landing-with-power in a field, which suggests that conditions have got to be sufficiently bad that you would have landed in a field had the runway not been there.
This does not suggest that you get a free landing because you're waiting for the weather at the destination to improve, or because, while you've got plenty of fuel to turn straight round and get home again, you've come for a day out and you're b*gg*red if you're not going to land away somewhere. Foolishly taking off with insufficient fuel to do anything except re-cross the channel and land on the first flat space you can find would end up as something qualifying for an (undeserved) free landing, it seems to me, but I can't believe that 15 people got themselves into that stiuation at the same place on the same day.