“The meeting will be tomorrow afternoon and the attendees will cover the most significant investors in the UK in such areas as banking, life sciences, technology and the manufacturing sector,” a spokesman at May’s Downing Street office said.

Japanese firms have spent billions of pounds in Britain over recent decades, encouraged to set up in the country by successive governments promising a business-friendly base from which to trade across the continent.

Brexit uncertainty draws Asian investors to London properties

Carmakers Nissan, Toyota and Honda began operating in Britain from as early as the 1980s and now build nearly half of Britain’s 1.67 million cars, the vast majority of which are exported.

Nissan, which runs Britain’s single biggest car factory in Sunderland, northern England, will be among the attendees at Thursday’s meeting but would not be drawn on topics of discussion.

It has agreed to build two new models at the site after what a source said was a government promise of extra support in the event that Brexit hits the competitiveness of the plant. 

Many businesses fear Britain could face a disorderly Brexit that would weaken the West, imperil Britain’s US$2.7 trillion economy and undermine London’s position as the only financial centre to rival New York. 

Like the rest of the industry, they are concerned that their exports could face tariffs of up to 10 per cent and be subject to lengthy customs delays after Brexit.

Banks Nomura, Daiwa Securities and Sumitomo Mitsui Financial Group have London bases but have already decided to set up operations in Europe to retain access to the single market as they await clarity on future trading arrangements.

Many Japanese drug companies have made Britain their European base in recent years and are worried, like their peers, about the future of drug regulations, with any divergence with the European Union likely to pose regulatory challenges.

Concerns about Brexit also remain high among Britons living in the EU - but they now have some hope after a group of five British citizens won a landmark legal ruling that will result in their case being heard in the European Court of Justice (ECJ). 

It is in UK’s interest to boost ties with China

The five, who have settled in the Netherlands, told an Amsterdam court that their existing EU citizenship could not be removed because of the UK referendum; the court has now passed on their case to the ECJ for further development.

A spokesman for “Brexpats – Hear Our Voice,” which led the challenge, said: “We are grateful to the court and obviously delighted with the decision. However, this is just the first step in clarifying what Brexit could mean for our EU citizenship. 

“This case has always been about seeking clarification, not only for the 46,000 Brits living in the Netherlands, but also for all the 1.2 million Brits living in other EU countries. 

“As has been demonstrated in recent days, what Brexit means is still extremely unclear. You cannot play with the lives of 1.2 million people as if they are pieces on a chessboard.” 

The lobby group, the five Britons and the Commercial Anglo Dutch Society were the named claimants in the case that was funded and supported by Jolyon Maugham, the Queen’s Counsel behind a series of Brexit legal challenges in Britain. 

The judge will issue two draft questions to be put before the ECJ within the next two weeks.