The last Shah of Iran, Shah Reza Pahlavi, was a huge Rangers fan:
The diplomats pressed for yet more royal visits, ideally with the shah comping to Britain again. The queen was completely horrified. The palace stalled and said she would be pleased to do something for the Royal children. Accordingly, in 1974, a tour of Scotland for the shah’s three children was arranged. The eldest son, Crown Prince Reza, was fascinated by all things tartan and was a manic Rangers fan. So the highlight was a match at Edinburgh‘s Easter Road Stadium between the Rangers and Hibernian on July 31, 1974. The crown prince fortified himself beforehand by having two helpings of hamburgers, chips, beans, and peas at the nearby Epicure Snack Bar. He then spent the match cheering wildly at each of the Rangers’ three goals. The only moment of anxiety for the British security team was when he insisted on shaking hands with many Rangers fans after the third goal.
Aldrich, Richard J and Cormac, Rory, Crown, Cloak, and Dagger: The British Monarchy and Secret Intelligence from Victoria to Elizabeth II, p257
Definitely a little football diplomacy…