Found a copy of the Operations Manual amid the debris here.

Section 5.9 "Club Racing Schedule Procedures"

5.9.4: "Normally, no two race events will be held on the same day within a reasonable day's driving distance unless the Regions involved agree. (This does not apply to National races)"

Not quite what I remembered...and there is a certain ambiguity in that language...but you'd have a hard time constructing an argument that LRP <> The Poke is greater than a "reasonable day's driving distance".