A critic of tax havens who featured in a BBC documentary about the Brink’s-Mat gold bullion robbery was misrepresented, according to Ofcom.

The Gold: Inside Story, which aired in March, traced how armed men broke into the Brink’s-Mat security depot near London’s Heathrow Airport in November 1983.

It also focused on where the missing gold ended up and banking practices at the time.

In a report published on Monday, media watchdog Ofcom said it had upheld a complaint of “unjust or unfair treatment” from Arthur Lewis-Grey, who says he worked for offshore tax havens as a lawyer before leaving and becoming critical of them.

Mr Lewis-Grey claimed in the Ofcom report that the documentary re-used footage of him “shorn of context” from an ITV World In Action programme, broadcast in the 1980s.

He said the BBC programme made him look like an “enthusiastic seller” of offshore financial services in the Isle of Man, “regardless of the outcome”.

Mr Lewis-Grey added that he had “been moved from the world of tax avoidance and evasion to commenting apparently frivolously on serious and murderous crime”.

He said he currently works in regulatory compliance for banks, and his appearance “runs contrary to (his) work in those organisations”.

Mr Lewis-Grey said “a number of people have since contacted (him) having viewed the programme”.

The disposal of the Brink’s-Mat bullion, worth £26 million, was among the largest international money-laundering operations of the time and left a string of killings in its wake.

This resulted in the complainant being misrepresented in a way that had the potential to materially and adversely to affect viewers’ opinions of him

Much of the three tonnes of stolen gold has never been recovered and some of the suspects were not convicted.

The BBC said the footage was a small part of a wider analysis of the state of the tax avoidance industry in the 1980s, and how it facilitated the laundering of the proceeds of crimes.

The broadcaster also said Mr Lewis-Grey’s contribution was “sufficiently brief” so viewers could not assign him a motive or think he was an “enthusiastic seller” of offshore services.

However, the corporation agreed there should be “greater clarity” and said it has made “strenuous efforts to resolve the issue”, including removing the clip from the BBC iPlayer version.

The BBC also said it would not rebroadcast the show in the original format or sell to other broadcasters with that segment.

Ofcom said Mr Lewis-Grey was unnamed and “shown very briefly” so it would be “unlikely” that viewers would associate him specially with commenting on the Brink’s-Mat robbery.

However, the broadcast watchdog also said that without the context that he was a critic of tax havens, then viewers might have seen him as “advocating the benefits of offshore financial services”.

The watchdog said: “Ofcom considered that the re-use of the interview footage of Mr Lewis-Grey in the BBC programme was not presented in an appropriate context, and that this resulted in the complainant being misrepresented in a way that had the potential to materially and adversely to affect viewers’ opinions of him.

“Ofcom considered that this created unfairness to the complainant in the programme as broadcast.

“Ofcom has upheld Mr Lewis-Grey’s complaint of unjust or unfair treatment in the programme as broadcast.”

A BBC spokeswoman said the corporation noted the findings of Ofcom and declined to comment further.

The documentary accompanied a six-part series called The Gold, starring Hugh Bonneville, Jack Lowden and Dominic Cooper, which began airing in February.

The series followed the decades-long chain of events after what was described as “the crime of the century”.