More than 50 British nationals working for the European commission in Brussels have obtained Irish passports, which can help secure career progression, it has emerged.

Data released by the commission shows 120 officials with British nationality have secured additional passports of an EU state since March 2017, when the official article 50 notice was given that the UK was leaving the bloc.

According to the Irish broadcaster RTÉ, 10% of the 569 Irish passport holders working for the commission were originally British passport holders.

Anyone with an Irish parent, or a grandparent born in Ireland is entitled to an Irish passport. Securing dual nationality with another member state may improve the career prospects of British citizens working in EU institutions but it is not guaranteed.

To be eligible for an EU career, candidates must be a citizen of an EU country and be entitled to full rights as an EU citizen.

Timeline From Brefusal to Brexit: a history of Britain in the EU Show Brefusal The French president, Charles de Gaulle, vetoes Britain’s entry to EEC, accusing the UK of a “deep-seated hostility” towards the European project. Brentry With Sir Edward Heath having signed the accession treaty the previous year, the UK enters the EEC in an official ceremony complete with a torch-lit rally, dickie-bowed officials and a procession of political leaders, including former prime ministers Harold Macmillan and Alec Douglas-Home.

Referendum The UK decides to stay in the common market after 67% voted "yes". Margaret Thatcher, later to be leader of the Conservative party, campaigned to remain. 'Give us our money back' Margaret Thatcher negotiated what became known as the UK rebate with other EU members after the "iron lady" marched into the former French royal palace at Fontainebleau to demand “our own money back” claiming for every £2 contributed we get only £1 back” despite being one of the “three poorer” members of the community. It was a move that sowed the seeds of Tory Euroscepticism that was to later cause the Brexit schism in the party. The Bruges speech Thatcher served notice on the EU community in a defining moment in EU politics in which she questioned the expansionist plans of Jacques Delors, who had remarked that 80% of all decisions on economic and social policy would be made by the European Community within 10 years with a European government in “embryo”. That was a bridge too far for Thatcher. The cold war ends Collapse of Berlin wall and fall of communism in eastern Europe, which would later lead to expansion of EU. 'No, no, no' Divisions between the UK and the EU deepened with Thatcher telling the Commons in an infamous speech it was ‘no, no, no’ to what she saw as Delors’ continued power grab. Rupert Murdoch’s Sun newspaper ratchets up its opposition to Europe with a two-fingered “Up yours Delors” front page. Black Wednesday A collapse in the pound forced prime minister John Major and the then chancellor Norman Lamont to pull the UK out of the Exchange Rate Mechanism. The single market On 1 January, customs checks and duties were removed across the bloc. Thatcher hailed the vision of “a single market without barriers – visible or invisible – giving you direct and unhindered access to the purchasing power of over 300 million of the world’s wealthiest and most prosperous people". Maastricht treaty Tory rebels vote against the treaty that paved the way for the creation of the European Union. John Major won the vote the following day in a pyrrhic victory. Repairing the relationship Tony Blair patches up the relationship. Signs up to social charter and workers' rights. Ukip Nigel Farage elected an MEP and immediately goes on the offensive in Brussels. “Our interests are best served by not being a member of this club,” he said in his maiden speech. “The level playing field is about as level as the decks of the Titanic after it hit an iceberg.” The euro Chancellor Gordon Brown decides the UK will not join the euro. EU enlarges to to include eight countries of the former eastern bloc including Poland, Hungary and the Czech Republic. EU expands again, allowing Romania and Bulgaria into the club. Migrant crisis Anti-immigration hysteria seems to take hold with references to “cockroches” by Katie Hopkins in the Sun and tabloid headlines such as “How many more can we take?” and “Calais crisis: send in the dogs”. David Cameron returns from Brussels with an EU reform package - but it isn't enough to appease the Eurosceptic wing of his own party Brexit referendum The UK votes to leave the European Union, triggering David Cameron's resignation and paving the way for Theresa May to become prime minister Britain leaves the EU After years of parliamentary impasse during Theresa May's attempt to get a deal agreed, the UK leaves the EU.



However, in a notice issued after article 50 was invoked, the commission said: “The commission has taken note of the fact that a number of UK nationals among its staff have requested or may request a change towards a different first nationality. These changes are of an exceptional nature and therefore deserve a specific handling.

“As a consequence, staff members from the United Kingdom who declare a change of nationality after 29 March 2017 shall still be considered to have kept the UK nationality as first nationality for the purpose of ensuring a balanced representation of staff within the commission, notably at middle-management and senior management level,” said an official notice.

This is to ensure staff nationalities are in proportion to the membership of the union.

UK nationals in the commission were not the only Britons to have sought security in dual EU-UK nationality.

Last month, it emerged that 1,403 British nationals in Belgium had naturalised and have Belgian passports, up from 506 in 2016 and 127 in 2015.

This is part of an EU-wide trend, with more than 350,000 UK citizens living in Britain or a member state opting for dual nationality as a post-Brexit insurance policy.