The rate of capital gains tax in the American state of Delaware, where Mr Banbury intends to incorporate his new company if the Government goes ahead with the tax increases, is 6.6pc on annual gains of over $60,000 (£46,000).
According to HM Revenue and Customs estimates, a 10 percentage point increase in the higher rate of capital gains tax would cost the Exchequer £2bn of revenue in 2027-28, as investors change their behaviour.
Mr Banbury spends part of his time in Palo Alto and Silicon Valley, known for its thriving technology start-up ecosystem, which is estimated to be worth around $2.3 trillion by consultancy firm Start-Up Genome. It is also home to a number of talented British entrepreneurs that the Government must fight to win back, he believes.
He said: “The financial environment is definitely part of why Silicon Valley is thriving. I don’t think the Exchequer realises who they have lost and who they haven’t. There are British entrepreneurs in the US with immense power and phenomenal ideas that should be in the UK.
“If we lose the top-tier entrepreneurs from the UK, we cannot measure the consequence in capital gains tax loss – we will measure it in the overall opportunity and profitability of the British economy over the next 10 years. The real loss will never appear on the UK’s tax revenues.
“I understand that Labour needs to balance the books, and Reeves is really short of options – partly because of their manifesto [in which Labour committed to not raising income tax, national insurance or VAT].
“But we won’t be able to fix the NHS unless we get the cash from top businesses. What will happen in 10 or 15 years’ time if the biggest opportunities are dragged to America, and we are left with everything they couldn’t be bothered with?
“[The Government has] decided to pick on something that will mortgage the nation’s future. There are new forms of technology that are going to transform industry – artificial intelligence (AI) is just one of them – and the US tech world will forge ahead at the expense of the UK.”