Sir James Dyson has moved his main address to the UK, new company filings revealed on Wednesday, as it emerged that the billionaire exchanged private messages with Boris Johnson about tax issues during the pandemic.

Sir James is now domiciled in Britain, after relocating to Singapore two years ago.

Details for Weybourne, the business that controls Sir James’s fortune, were updated on Tuesday to show a change in the “new country/state usually resident” section for the entrepreneur, with the UK now listed.

Sir James still owns a property in Singapore and continues to split his time between there and Britain, a source said.

On Wednesday, it emerged that after agreeing to make ventilators for the UK during the early phase of the Covid-19 outbreak, he sent text messages to the Prime Minister asking him to alter tax rules.

The requested changes were aimed at ensuring staff based abroad would not pay extra tax if they came to the UK to work on the ventilators initiative. Weeks later, the tax rules for non-residents coming to the country for Covid-related projects were relaxed for a temporary three-month period.

Government sources said the change benefitted a wider group, including non-resident health professionals and vaccine researchers.

A Dyson spokesman said: “There was no benefit to James Dyson in relation to the work he undertook on the ventilator challenge. Neither Dyson nor Weybourne sought or received any benefit either.”

He added that Dyson voluntarily absorbed the £20 million cost of the contribution “in support of a national emergency”.

A spokesman for Sir James also confirmed the move back to the UK, adding that the company “does not comment on private family issues. In respect of corporate entities that made the filing, nothing has changed”.

He added that the billionaire remained one of the largest UK taxpayers, contributing more than £100 million last year. Sir James is ranked as the country’s richest person with a £16 billion fortune when his family is included.

Texts leaked to the BBC showed that Sir James contacted Mr Johnson directly in March 2020, and said “sadly” it seemed the Government did not want him to proceed on the ventilator initiative.

The message was sent after he had written to the Treasury asking for reassurances on the tax issue for non-resident staff, but had received no reply.

Mr Johnson responded by text: “I will fix it tomo! We need you. It looks fantastic.”

The Prime Minister struck a defiant tone after the texts were laid bare, amid Labour claims of “sleaze and cronyism”. He told the Commons he made “absolutely no apology at all” and said he was “happy to share all the details” of the exchanges as there was “nothing to conceal”.

Sir James said: “When the Prime Minister rang me to ask Dyson to urgently build ventilators, of course I said yes. We were in the midst of an national emergency and I am hugely proud of Dyson’s response. I would do the same again if asked.”

He added it was “absurd to suggest that the urgent correspondence was anything other than seeking compliance with rules”.

It was the third time that details of ministers’ private communications have been leaked in recent weeks.

Downing Street said on Wednesday that no leak inquiry had been launched, but Sir Iain Duncan Smith called for the national security adviser to investigate.

Who's behind the Westminster leaks?

Most ministers anticipate that they will face the odd controversy while serving in Government.

What they do not expect, however, is their private text and WhatsApp messages appearing in the public domain and fuelling these rows. Yet that is precisely what has happened in a stream of incidents in recent weeks, which Government insiders now fear could swell into a full-blown torrent of leaks.

The Prime Minister, the Chancellor and the Health Secretary have all had details of their private correspondence emerge in the media.

On Wednesday, Boris Johnson’s text exchanges with Sir James Dyson found their way into the hands of the BBC. The corporation made clear in its report that it had “seen” the messages in which Mr Johnson pledged to “fix” tax changes requested by the entrepreneur.

Meanwhile, last month the existence of text exchanges between Rishi Sunak, the Chancellor, and former prime minister David Cameron over Greensill Capital, the collapsed lender which employed Mr Cameron, were reported in The Sunday Times.

Questions were raised about the former Tory leader reaching out to Mr Sunak directly – and texting his personal rather than ministerial mobile.

It is understood that Government officials remain stumped about how the existence of the texts was made known to the press.

Matt Hancock has also been snarled by leaks of private communications. Last month, The Guardian published details of a conversation over WhatsApp between him and a former neighbour who was supplying the NHS with coronavirus test tubes.

The Health Secretary messaged Alex Bourne, a former publican, about a story set to appear about the pair in the newspaper. The messages suggested an “easy familiarity between the men” and that the latter “may have downplayed his relationship with Hancock in public”, The Guardian said.

Various theories abound over the source of these leaks – although there is no suggestion so far that they have originated from the same place.

Nonetheless, there may yet be a connection – in that one may have inspired another.

Senior ministers talk of the dangers of “leak culture” – the fear that one person taking the risk to leak damaging information emboldens others to follow suit.

Finger pointing is common in Westminster, and behind closed doors speculation has been rife about whether a politician with a vendetta against a rival, a mischief-making adviser, or a Left-leaning official who opposes the Government could be behind one or other of the leaks.

“There’s definitely a sense that some stuff is coming from officials, that it’s a knifing,” said one senior Tory.

Another source, who works in Government, insisted that “it’s impossible to tell”, however.

Some look further afield at the potential hacking threat from foreign powers. Sir Iain Duncan Smith has questioned whether a hostile state actor such as China or Russia could have breached the security of Mr Johnson or Sir James’s phones.

The former Tory leader called for an investigation into the Prime Minister’s phone led by Sir Stephen Lovegrove, the national security adviser.

In a move that surprised some Tory backbenchers, Downing Street clarified that no leak inquiry had been launched into the emergence of Mr Johnson’s texts.

But if the pattern continues to be repeated, it is only a matter of time until stiff action is taken.