The case involved an ‘off the record’ background briefing of the press in June 2012 given by Harnett, who is now retired, where the information disclosed was only slightly related to the case that was being held before the First Tier Tribunal (FTT) regarding Ingenious film schemes.

The briefing took place before Ingenious had decided to commence legal proceedings at the FTT.

HMRC tried to justify the briefing claiming that it had tried to form good relations with the media and wanted to publicise its views regarding elaborate tax avoidance schemes.

Despite this, the five judges decided that this did not justify a senior official, or anyone working for HMRC, discussing the affairs of taxpayers with the media. They also did not accept the defence that Harnett did not expect his comments to be reported.

An Ingenious spokesperson said: ’We are delighted that the Supreme Court has unanimously found in our favour. This was never about restricting HMRC's ability to collect taxes, nor was it about preventing the press from investigating public interest stories.

‘Consistent with HMRC’s own guidelines, this was simply about upholding the basic legal principle that HMRC owe a duty of confidentiality to each and every tax payer and their affairs should not form the subject of “off the record” background briefings to the media.’

HMRC scored a partial win against Ingenious in the FTT over film and game investment schemes. The case was over a disputed £1bn of tax and interest that HMRC was trying to reclaim from Ingenious over a dispute relating to film and game investment schemes, which HMRC claimed was avoidance. The hearing was held over 48 days from November to December 2015.

James Badcock, partner and head of tax and estates at Collyer Bristow, said: ‘HMRC went much too far – they should not be providing confidential information about taxpayers to the media.

‘HMRC leaking its intention to aggressively pursue a taxpayer to the press brings unnecessary aggravation to a dispute.”

‘Every taxpayer, whatever HMRC thinks they have done has a right of confidentiality until the results of a tax dispute become a matter of public record.’

Hartnett has now retired from HMRC. Standard policy at HMRC is never to discuss or comment on the affairs of taxpayers, whether they are individuals or corporations.

A HMRC spokesperson said: 'Having earlier won this case in both the High Court and Court of Appeal, HMRC is naturally disappointed by the judgment handed down by the Supreme Court.

'HMRC defended this case because it considered that the disclosure made by Mr Hartnett was lawful. However, the Supreme Court has decided otherwise and we will examine the judgment in detail.

'It is important to clarify that this judgment has no bearing on the three Ingenious film partnerships considered by the first tier (tax) tribunal, where HMRC was successful. This protected around £400 million in revenues for the exchequer.'