<P> Dual nationals holding a Commonwealth citizenship that recognise the British monarch as head of state are entitled to use the styling . Common usage varies from country to country: for instance, dual Bahamian - American citizen Sidney Poitier, knighted in 1974, is often styled' Sir Sidney Poitier', particularly in connection with his official ambassadorial duties, although he himself rarely employs the title . </P> <P> The permissibility of using the style of' Sir' varies . In general, only dynastic knighthoods in the personal gift of the Sovereign and Head of the Commonwealth--the Order of the Garter, the Order of the Thistle and the knighthoods in the Royal Victorian Order--are recognised across the Commonwealth realms, along with their accompanying styles . Knighthoods in the gift of the government of a Commonwealth realm typically only permit the bearer to use his title within that country or as its official representative, provided he is a national of that country; Commonwealth realms may consider knighthoods from other realms to only be foreign honours . For instance, Anthony Bailey was reprimanded by Buckingham Palace and the British government in 2016 for asserting that an honorary Antiguan knighthood allowed him the style of' Sir' in the UK . </P> <Ul> <Li> Knight Commander or Knight Grand Cross of the Royal Victorian Order (KCVO / GCVO) </Li> </Ul> <Li> Knight Commander or Knight Grand Cross of the Royal Victorian Order (KCVO / GCVO) </Li>

How to address someone with a sir title