A Post Office boss blamed cash shortfalls caused by computer glitches on branch managers “with their hand in the till”.
An email written by Alan Cook, who was managing director of the group from 2006 to 2010, has been read out to the public inquiry into the Horizon IT scandal.
Giving evidence on Friday, he said it was an expression he would “regret for the rest of my life”.
Mr Cook was at the helm when about 200 prosecutions were brought against subpostmasters.
Despite being in charge, he said he was “unaware” it was the Post Office that had brought criminal proceedings against individuals – and that during his time in the top job, it did not feel like the Post Office “had a crisis on its hands”.
An email sent by Mr Cook in October 2009 to a Royal Mail Group press officer said: “For some strange reason there is a steadily building nervousness about the accuracy of the Horizon system and the press are on it now as well.
“It is… strange in that the system has been stable and reliable for many years now and there is absolutely no logical reason why these fears should now develop.
“My instincts tell me that, in a recession, subbies (subpostmasters) with their hand in the till choose to blame the technology when they are found to be short of cash.”
Pressed over his remarks at the inquiry, Mr Cook said: “Well that’s an expression I will regret for the rest of my life. It was an inappropriate thing to put in an email – not in line with my view of subpostmasters.”
Hundreds of people were wrongly convicted of stealing after bugs and errors in the Horizon accounting system made it appear as though money was missing at their branches.
Victims faced prison and financial ruin, others were ostracised by their communities, while some took their own lives.
Fresh attention was brought to the scandal after ITV broadcast the drama Mr Bates Vs The Post Office, prompting government action.
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Alan Bates speaks at Post Office inquiry
Earlier, as he began giving evidence, Mr Cook said he wanted to “put on record most strongly my personal apology and sympathies with all subpostmasters their families and those affected by this”.
He also told the inquiry: “I was unaware that the Post Office were the prosecuting authority.
“I knew there were court cases but didn’t realise that the Post Office in about two-thirds of the cases had initiated the prosecution as opposed to the DPP (director of public prosecutions) or the police.”
During his time as non-executive director of the Post Office, Mr Cook said it was his “regret” he failed to properly understand minutes of a meeting which said the organisation had a “principle of undertaking prosecutions”.
He said: “It never occurred to me reading that that the Post Office was the sole arbiter of whether or not that criminal prosecution would proceed.”
Mr Cook added: “I had never come across a situation before that a trading entity could initiate criminal prosecutions themselves.
“I’m not blaming others for this, it’s my misunderstanding but I’ve just not encountered that type of situation.”
He acknowledged he should have known the Post Office was making prosecutorial decisions.
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Jailed subpostmistress watches evidence
Counsel to the inquiry Sam Stevens asked: “Your evidence is still that in no point in the years that you were the managing director, (nobody) in the security or investigations team raised the fact that they made decisions to prosecute?”
Responding, Mr Cook said: “That is my position, definitely.”
He went on: “I never asked that question – well I did obviously when we got to the Computer Weekly article (in 2009) which we’ll get to but prior to that point I had gone through not picking up that.
“I’m not blaming them for not spelling it out enough, to be frank I’m blaming me for not picking up on it.”
During his time at the Post Office, Mr Cook said in his witness statement it was not apparent there was a problem with the Horizon system, pointing out that financial audits “did not identify a systemic issue”.
He added: “It is a matter of deep regret to me that I did not recognise that the early issues raised in 2009 were an indication of a systemic issue before I left POL (Post Office Limited) in February 2010.
“In addition, I have since learned that the annual rate of prosecutions brought by POL in the seven years prior to my appointment (ie since 1999) had remained steady during that time, and continued to remain steady during my time in office and thereafter. It did not feel, at the time, that POL had a crisis on its hands.”
