Boris Johnson's dad has taken up French citizenship despite having backed Brexit to be a success for Britain.
Stanley Johnson, an ex-member of the European Parliament, has received his new passport after filing an application at the consulate in London in November last year.
The sixth-month deadline for the country's justice ministry to object has elapsed and he was officially approved on Wednesday.
The 81-year-old had initially been in favour of remaining in the EU at the time of the referendum in 2016 - voting as such, before making a U-turn when Leave won.
Stanley has ties to France through his mum, Irene Williams, but was born in Cornwall.
He speaks fluent French and previously said his bid for citizenship was "a question of obtaining what I already have".
French law usually stops the offspring of citizens successfully claiming nationality if they have been abroad for over 50 years without making use of their rights.
However, a clause does mean such a person can be considered if they prove "concrete ties of a cultural, professional, economic or family nature".
France's justice ministry said in a statement: "Based on the facts in his application, and without a refusal by the justice minister, Mr Stanley Johnson acquired French nationality on 18th May, 2022.
"This decision concerns only Mr Stanley Johnson and does not extend to his descendants."
During the 1970s, Stanley had moved his family to Brussels, Belgium, while he was working for the European Commission.
His being a Remainer had put him at odds with his son - the now PM who had just completed an eight-year stint as Mayor of London when the country went to the polling stations.
Boris became a key figure in the Vote Leave campaign, masterminded by Dominic Cummings, who would then play a similar role in getting him into No10 before they spectacularly fell out last year.
And despite the now-Prime Minister's support for Leave, his siblings Rachel and Jo also backed Remain.
Stanley eventually backtracked, calling Brexit "probably a good idea", citing Russia's invasion of Ukraine having "shaken" his faith in the political and economic union.
In a column for the Daily Telegraph titled 'The war in Ukraine has shown me that I was wrong about Brexit' in April, he slammed the "naivety of our European neighbours", particularly their "weak policies" towards Vladimir Putin.
"At this moment, you have to say that Europe needs to pull its socks up," he added.
Stanley previously told radio station RTL in December 2020 he had applied for a French passport because: "If I understand it correctly, I am French.
"For me it's a question of obtaining what I already have and I am very happy about that.
"I will always be European, that’s for sure. You can’t tell the English 'you’re not European'."
He added that Europe is more than just the EU and single market.
