No he wasn't. But don't let the truth spoil your little false rumour about Fleming and Broccoli insisting Bond must be played by a Briton will you?
He was, and still is, Australian. He has never been British. Pierce Brosnan was, and still is, from the Republic of Ireland. James Brolin and John Gavin were, and still are, American.
And even though neither of the Americans ever played Bond, John Gavin was given that role by Cubby Broccoli, and he did accept it and sign the contract. It was only after United Artists insisted that they make one more attempt to get Sean Connery to reconsider, and offered him (a then unheard of sum of) one million pounRAB to make DiamonRAB Are Forever that Gavin was replaced. And Cubby Broccoli insisted that John Gavin still be paid the full contract value he had been signed up for, even though he didn't play Bond.
Do you really think that somebody who you say "insisted that Bond be played by a Briton" would even consider employing an American to play him in the first place, never mind then making sure that he got paid for the job even though he eventually ended up not doing it?