Not quite true that Fleming never set a Bond adventure in an English speaking Commonwealth country. Apart from the fact that Jamaica, the Bahamas and Bermuda are undeniably English speaking and two are members of the Commonwealth (Bermuda is a British Overseas Territory) - didn't part of "For Your Eyes Only" - the short story that is - take place in Canada, with Bond being assisted by an RCMP officer in his pursuit of Von Hammerstein and his cronies?
Yes. The bedtime story Bond tells Viv in TSWLM also puts Bond in Toronto, Canada.
No criticism intended of anyone posting here - rather the author of "The Politics Of James Bond".
(Incidentally, I'm unsure about the start and end of the book Diamonds Are Forever. I always thought they were set in Sierra Leone, another at that time British Colonial territory. Bond even turns up at the end controlling a British Army Bofors gun to shoot down ABC's helicopter. But Kingsley Amis' The James Bond Dossier has the location as French Guinea.)
"The bush grew more or less at the junction of three African states. It was in French Guinea but only about ten miles north of the northernmost tip of Liberia and five miles east of the frontier of Sierra Leone." (ch.1)
Bill Tanner's cable to Bond reads in part, "This tends confirm our suspicion that diamonds originate Sierra Leone mines thence smuggled over frontier into French Guinea [...] RAF CANBERRA awaits you Boscombe Down for immediate onward flight tomorrow night to Sierra Leone signed COS." (ch.24)
In other words, Bond flies to Sierra Leone. The diamonds are smuggled out of a Sierra Leone mine, but the handover happens across the border in French Guinea which is where Bond shoots down Spang's helicopter.