Britain changed their edict that you could not renounce British citizenship around 1958. I was naturalized in 1957 so I am a dual national...Brit and U.S. My older brother naturalized automatically when he completed his Army service in 1958, so he’s 100% American (naturalized)...he can’t run for President, tho’.
A guy from my home town was a naturalized citizen born in Scotland. He always kept his UK passport updated so when he was traveling he had both passports. His reasoning was in case the plane was highjacked, he figured he would show the highjackers the passport that would least likely get him killed. He also had a son who was born two years before they immigrated. Though he became a citizen, he did not naturalize his son. The kid could throw 90+ in HS, and the father figured his UK citizenship would take him out of the MLB draft and keep him a free agent for a bigger signing bonus, like guys from the DR. Signed with Atlanta and later made the show with Cleveland, beat the Yankees a few times.