Written by: George Prior Brexit Britain has already lost three years - and the nightmare could last well beyond the new Halloween deadline, warns the boss of one of the world’s largest independent financial advisory organizations.The warning from Nigel Green, the chief executive and founder of deVere Group, comes as news breaks on Thursday that factory shutdowns designed to cope with disruption from a March 29 Brexit that never came, slashed UK car production in April by almost 45 per cent.It also follows Jeremy Corbyn confirming that Labour will back a referendum on any Brexit deal.Mr Green says: “Brexit has thrown Britain into a profound existential crisis.“It has cost Britain three lost years of opportunity. Brexit has almost entirely overtaken the public sphere in Britain. All of Parliament’s time and energy is vested in Brexit. It appears nothing else is getting done. And so much needs to be done.“Imagine what amazing social and economic progress could have been achieved if the media, political life and the civil service had been dominated by ‘best in class’ individuals and organisations building an inclusive, long-term, sustainable economic growth strategy for the last three years?“Imagine if these three years had been about retaining existing and welcoming new investment into the UK?“Imagine if the industries of the future, such as fintech, blockchain and clean energy, had been developed to secure jobs and wealth creators of the next generation?“Imagine if Britain hadn’t spent three years inflicting reputational damage upon itself on the world stage?“But instead, the UK has lost three years going around in circles trying to construct a deal that gives us some of what it’s got now.”Related: China’s Looming Current Account Deficit Will Have Consequences for Us All He continues: “Brexit Britain has cost billions upon billions of pounds.“Indeed, it has cost the UK economy a staggering £66bn in just under three years, according to S&P Global Ratings.“Speaking from experience, the lack of confidence in the UK’s vital financial services sector – which contributes 6.5 per cent to Britain’s GDP – is at an all-time low.“Following years of uncertainty and a lack of leadership from all parties, many companies across the sector have relocated parts of their business or key staff to places like Paris, Luxembourg, Dublin, Frankfurt and Amsterdam, or setting up legal entities in the EU. Once they’ve gone, they are unlikely to return. And this is just one sector.“There’s also been the significant drop in the value of the pound. This has contributed to reducing people’s purchasing power. Weaker sterling means imports are more expensive, with rising prices typically being passed on to consumers.“For the government’s part, the Treasury has allocated £4.2 billion towards government departments for Brexit preparations since 2016; the 2017 general election which was held due to Brexit ramifications cost £269m; and let’s not forget, the £39bn “divorce bill” agreed with the EU.”Mr Green goes on to add: “The ongoing Brexit nightmare is unlikely to end on Halloween.“After three years, the uncertainty grows rather than recedes. Who will be the Prime Minister that will take the UK out of the EU? Will there be a second referendum and what would be on the ballot paper? How does the rise and rise of the Brexit Party fragment politics further? Will Britain leave with no deal? What impact would operating on WTO rules mean for the world’s fifth largest economy and its trading partners?”The deVere CEO concludes: “With so many serious and far-reaching questions hanging ominously unanswered - and more growing each week - Brexit Britain’s Lost Years are not even close to being over.“The haemorrhaging of opportunity and money will continue far beyond the deadline.“It is perhaps therefore unsurprising that UK and international investors in UK assets are responding to the uncertainties posed by Brexit by considering removing their wealth from the UK.”