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Bugs identified in Post Office software

10th Jul 2013
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A report by forensic accountants that found computer bugs in the Post Office’s computer system has underlined the importance of basic bookkeeping and staff training, experts say.

The report by Second Sight comes after UK sub-postmasters said they had been wrongly accused of theft, fraud and false accounting. Some lost their homes and a few went to prison.

Second Sight was hired by the Post Office to investigate a handful of the sub-postmasters' claims. Although the accountant's interim report found no evidence of systemic problems with the core software, it did find bugs in it.

It found two occasions, in 2011 and 2012, when the Post Office identified “defects” in Horizon that resulted in a shortfall of about £9,000 at 76 branches. The Post Office took a year to realise that the second computer defect had happened.

The Post Office later made good those losses and the sub-postmasters were not held liable.

Sub-postmasters criticised Horizon for being too complex, having unreliable hardware and having inadequate helpdesk support, the report found.

The Post Office said the report showed its system was effective but said it would improve training and support.

It also said it would:

  • Complete the review of cases started by Second Sight last year
  • A review chaired by an independent figure to determine how an independent safety net might be introduced to adjudicate in disputed cases in the future
  • A new “branch user forum” to provide a way for sub-postmasters and others to “raise issues and insights around business processes, training and support, directly feeding into the organisation’s thinking at the highest level”.

The Horizon IT system is used by about 68,000 people in more than 11,500 branches and processes over 6m transactions.

Fujistu refused to comment on the report.

Poor accounting controls?

It’s still unclear whether accounting errors were caused by computer error, poor working practices or lax safeguards against fraud.

As Second Sight’s report notes: “Our experience over many years, shows that even apparently robust controls sometimes fail to work, or can be circumvented by a determined and skilful person.”

The firm declined to comment further on Horizon.

What can accountants and their clients learn from the Post Office’s accounting problems?  

Vivian Cohen, partner at Frenkels Forensics, an accountancy firm specialising in forensic accounting, told AccountingWEB that he was hired to represent a sub-postmaster in court after the Horizon system showed a cash shortfall at the branch.

Cohen found that things weren’t so “clear cut” because Horizon wasn’t always reliable and other people in the Post Office had access to the accounting system – entering dates, money transactions and pension payments.

The sub-postmaster got a suspended sentence but Cohen said that he appeared “very stressed” and a “broken man” due to the stress of the court case.

“People can be sent to prison quite often on the basis of a computer error,” Cohen said.

Businesses can minimise the risk of accounting errors and fraud by regular reconciliations of transactions, which helps to spotting any cash shortfalls and working out what caused them, Cohen said.

He also said that accounting tasks such as cash handling, banking the cash and reconciling transactions should be done by separate people.

When Richard Anning, head of the IT faculty at the ICAEW, was first told about the alleged problems with Horizon in 2009 he said that an IT audit was needed.

He told AccountingWEB that the report on Horizon still leaves questions unanswered. "If the Post Office is reporting bugs [in Horizon] does it mean transactions are being double counted but it’s not apparent?”


Replies (9)

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David Winch
By David Winch
11th Jul 2013 09:25

A real problem

This is a real problem which I raised on AWEB as long ago as 2009.

What seems to have occurred on some occasions is that sub-postmasters have found cash 'shorts' showing up which (under their contracts with the Post Office) they have to make good.  If the sub-postmaster is unable or unwilling to make it good then he or she may have resorted to making additional (and false) entries on the Horizon system in an unwise attempt to hide or eliminate the 'short'.

When this has been discovered the sub-postmaster has faced criminal prosecution for theft and / or false accounting.  In these circumstances the dishonest making of a false entry on Horizon with the intent of avoiding having to make good an apparent 'short' does amount to the offence of false accounting.  In consequence in these cases very often the sub-postmaster will have been advised to plead guilty.

This has lead the Post Office in the past to say that there has been no evidence of any problem with the Horizon system.  But that, as we now know, does not tell the whole story.

A particular problem can arise in relation to lottery ticket sales because these sales are accounted for both via Horizon and via Camelot lottery terminal software.  In addition although the sales are accounted for in Horizon typically the lottery terminal is in the 'shop' rather than the 'Post Office' and so the cash takings are initially placed in the 'wrong' till and have to be transferred.  It can all get rather messy!

It is good to see that some progress appears to be being made in resolving the problems.


Thanks (1)
By chatman
11th Jul 2013 10:50

Prison Sentences Caused by PO Software Bugs

So have people gone to prison because of the Post Office software bugs or not? Is it likely that some people pleaded guilty in cases where they were innocent, and the fault was in the software?

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By Donald6000
11th Jul 2013 11:15

Basic book-keeping and Accounting

If sub postmasters and sub postmistresses are trusting this software then they need their heads testing. For what it's worth I think they put the snags into the system to discover who is honest and who is not; having worked for Royal Mail I know how paranoid they are and how much they try to jump on top of what they consider to be "fraud".

As an example of what these people are all about, may I say that I have been for jobs in the 1980/1990 period with both Post Office Counters and Royal Mail. With Royal Mail I sat in that big college near Mornington Crescent and did five hours worth of examinations at A Level standard. The tests for PO Counters were equally as hard and exhausting. Neither of the positions were awarded to me. Now I see that the staff don't even know basic book-keeping.

These are organisations that are grandstanding and will tell you their systems are beyond reproach. Now we find out that they are full of bugs. To be honest, I would not believe a single thing that I was being told by PO Counters and I would go so far as to state that their systems are full of bugs for the reason that they seek to viciously punish staff at random.



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David Winch
By David Winch
11th Jul 2013 11:21

Depends what you mean by innocent

It depends what you mean by innocent.

If the sub-postmaster has deliberately made false entries to cover-up an apparent 'short' then he is guilty of false accounting - even if there was in reality no 'short' just a 'computer error'.

You have to bear in mind that the sub-postmaster may have gone through at lot by the time the case arrives at court.  He may by then already have lost his business and livelihood.

He will have been advised that if he goes to jury trial and loses he will getter a stiffer sentence than if he pleads guilty.  In many cases a guilty plea will result in a suspended sentence.  So there is a real incentive to plead guilty and bring the nightmare to an end.


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By Donald6000
11th Jul 2013 11:39

Response to Davidwinch

I don't agree with your diagnosis of suspended sentence. Is it not the case that a pregnant woman/mother with children has been sent to prison because of these foul ups?

I want to know what kind of system of justice it is that allows a major corporation responsible for accounting for millions of customer funds to have a computer system that causes cash shortfalls? It seems to me that Post Office Counters should be in court on a charge of corporate negligence, not their poor employees.

I just hope that there is a massive compensation claim against both POC and the government for negligence and wrongful imprisonment.

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David Winch
By David Winch
11th Jul 2013 12:35


Certainly some people have gone to prison having been convicted of an offence as a sub-postmaster or employee using Horizon.  What I said was "in many cases a guilty plea will result in a suspended sentence".

There was even a case of a murder trial in which part of the evidence against the accused was that he was dishonest and an audit of his Post Office had shown a shortfall.  He was convicted of the murder - but how far the shortfall allegations were a factor in the jury's deliberations we shall never know.


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By Donald6000
11th Jul 2013 21:48

Prison (2)

 What I said was "in many cases a guilty plea will result in a suspended sentence".

This brings me back to my experience as an Appropriate Adult within the Hampshire Constabulary area. I am asking why it is that these people thought they had to plead guilty when it is obvious to me that the Post Office Counters system throws up anomalies. By the way, most people that I have met in the criminal justice system would not have pleaded guilty to something they had not done and I find that this is a strange situation which does not quite ring true.

Why would someone plead guilty when presumably it is well known that the Horizon system is a fault riddled system and in whose vested interest is it that these people pleaded guilty?

Very suspect.



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David Winch
By David Winch
12th Jul 2013 11:43

The Post Office position

The Post Office has always maintained that Horizon is a reliable system.

Most recently they have commented:

No system wide problems have been found in relation to the Horizon software . . .

The interim review makes clear that the Horizon computer system and its supporting processes function effectively across our network. As the review notes, it is used by around 68,000 people in more than 11,500 branches, successfully processing more than six million transactions every day. The review underlines our cause for confidence in the overall system.

In the face of this and where the defendant has indeed deliberately made incorrect entries on the system and where it is possible to do 'a deal' with the prosecution to, for example, plead guilty to 'false accounting' rather than face a charge of theft, and get the benefit of mitigation from a guilty plea (and thus a lighter sentence than on conviction after trial) then a defendant is very tempted to plead guilty (and will typically be advised to do so).

It may also be the case that the defendant will have said things in interview (under caution) with Post Office investigators which will be repeated in evidence and which amount to admissions of some improper actions.  Typically the sub-postmaster will have declined the option of having a solicitor present in the initial interview. (That is probably an unwise decision but one can understand why the sub-postmaster might want to keep initial enquiries relatively relaxed and informal.)

Counsel may well advise that the likelihood is that if the matter goes to trial by jury the jury will accept that the Post Office software is reliable - and the defendant's protestations of innocence are not.

I am bound to say that my personal view is that an innocent defendant cannot be sure that he or she will be acquitted by a jury and I would advise a defendant in these circumstances to give very serious consideration to a guilty plea.


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By mikewhit
12th Jul 2013 12:59


What with Prism and Snowden etc, I first thought this item was about your PC being bugged by unscrupulous parties after you installed software for eg. printing stamps !

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