When I was at Northolt we had a "book o'rools" that said who was entitled to what and when. As thick as QRs it was. We also had a Staish who spent nearly all his duty hours over on Southside, saluting visitors and engaging them in idle chat, while OC Operations ran the station for him.
Prime Ministers and Ministers were definitley salutable people, along with senior civil serpents (i.e. those who arrived in chauffeur driven government limo's), Commonwealth High Commissioners and foreign ambassadors on official duty and suchlike. Its hard to tell when a foreign ambassador is on official duty ( except the Aussie High Commissioner. He always shaved, and wore shoes and a shirt when he was "official" )