Language in an infamous Post Office document that categorised branch operators as "negroid types" was common in the public sector from the 1980s but continued to be used in the scandal-hit organisation until 2016, an inquiry has heard.

The document, which revealed that lawyers investigating post office operators in the Horizon computer scandal used a racist term to categorise black workers, first became public in May last year when it was released to campaigners seeking justice for those wrongfully prosecuted.

The public inquiry is examining how the post office pursued hundreds of branch owner-operators through the courts over account shortfalls based on evidence from the Horizon system, which was later shown to be faulty.

In written evidence, John Bartlett, the director of assurance and complex investigations at the Post Office since 2022, said the state-owned body had "used identity codes which described a person's racial origins in language that was outdated, offensive and reprehensible".

The document had categorised operators under investigation by the Post Office as "negroid types", along with "Chinese/Japanese types" and "dark skinned European types".

He said a fact-finding project, entitled Project May, had concluded that the categorisation had been inherited by the Post Office after it split from the Royal Mail Group in 2012 and that "identity codes (such as those identified in the document) were likely used in many public sector organisations as early as the 1980s".

In his evidence, Bartlett wrote: "Between 2008 and 2013, it appears Post Office understood that the use of identification codes was necessary as part of the prosecution process, which it saw 'as an externally imposed requirement', rather than it being driven by any internal policy."

The ending of prosecutions in 2013 led to the document falling out of use "rather than because of any identified issue with its contents" but there was evidence of it being shared as late as 28 June 2016, Bartlett told the inquiry.

He added that a second phase of Project May had been due to analyse "historic prosecution and charge data to consider whether the use of identity codes influenced charging or disposal decisions" but that this had been ditched in May 2024 by his boss, Sarah Gray, who is group legal director at the Post Office.

Bartlett wrote: "I was not involved in discussions about why the scope of phase 2 should be changed or how it should be changed."

He said the next phase would look at "developing future policy" in a way that learned "from project May", rather than conducting a "backward-looking exercise into the role of identification codes in decision-making in previous criminal investigations".

Bartlett also conceded that a number of investigators who had been involved in the wrongful prosecution of branch operators continued to be employed by the Post Office, adding that they no longer being in "postmaster facing roles" should be the least that should happen.

He said there was a wider "fear of decision making" in the Post Office's senior management today, adding that internally there were a "high number of reports through the Speak Up line ... commenting or reporting poor behaviour at head of dept level or [senior executive group] level", including bullying.

Bartlett also discussed the revelations last month that the Post Office had attempted to use Horizon IT transaction data to support a criminal case against a branch owner operator earlier this year.

He said Fujitsu had not categorically informed the Post Office that the data provided by the latest iteration of the Horizon system was unreliable and they had a "duty" to do so if that was the case.

Earlier this month, it was revealed that a senior Post Office executive had been accused by a whistleblower of instructing their team to destroy or conceal material of possible interest to the inquiry. Bartlett said that the Post Office had informed the inquiry and the incident was now being investigated by the Met police.