The UK is in prime position for growth despite Brexit due to rising global trade, according to a Conservative economics grandee who voted Remain.
Lord Jim O'Neill - a former Tory Treasury minister and former chairman of Goldman Sachs Asset Management - said Britain's growth performance is likely to be upgraded this year as China, the US and Europe show increased activity.
He was asked by the BBC if he and the majority of economic forecasters were too gloomy about the UK's prospects in the run-up to the vote to leave the European Union last June.
O'Neill replied: "I'm almost embarrassed to accept that it might sound like that.
"Because of course in principle I share the views of many that Brexit is a really weird thing for the UK to impose on itself from an economic perspective."
A study by Cambridge Econometrics for the Mayor of London, Sadiq Khan, earlier this month estimated UK growth would be 3% lower by 2030 than it would have been if Britain remained inside the EU's customs union and single market.
But O'Neill said: "If that's the worst that Brexit will deliver, then I wouldn't worry about it.
"Now, my own view is if we go for a really hard Brexit or a no-deal Brexit, we'll probably suffer more than that 3%.
"But if it is only 3%, what's going on with the rest of the world - helping us - and with productivity improving, that will easily dwarf a 3% hit over 13 years, easily."
Over the past six months economic forecasts for global growth have been lifted. China, the US and Germany have all published strong economic data and last October the International Monetary Fund upgraded its global growth forecast to 3.7% in 2018 from 3.6% in April.
Further upgrades are expected at the World Economic Forum in Davos, Switzerland when the world's key political and business leaders meet.
O'Neill quit the Tory benches when he resigned from his ministerial role in September 2016 and now sits as a crossbencher in the House of Lords.
The economist is famous for coining the term BRIC countries in the 1980s to describe the growing economic influence of Brazil, Russia, India, and China.