It's not just A/G operators that cause the problem. White Waltham is (usually) A/G and they take great care to be by the book.
Occasionally visiting aircraft cause problems by repeatedly asking for landing clearance etc. and can't seem to understand that an A/G station can't do that. Is this caused by the pilot not having read/forgotten CAP413 or is it caused by them in the past being in contact with too many "Heathrow Tower" A/G stations?
--Mik