UKGI00013913 - Draft Letter from Edward Davey MP to Karen Lumley MP re: concerns raised by constituents about Post Office Horizon system

Evidence on official site

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Edward Davey MP
Karen Lumley MP Our ref: 236583
House of Commons Your ref
London
SW1A OAA
February 2011

Thank you for your letter of 18 February setting out concerns raised by
constituents about Post Office Ltd’s (POL) Horizon computer system.

The issues raised in your letter are, however, operational and contractual matters
between POL and individual subpostmasters and I should make clear that neither
I nor the Department can intervene in cases which are sub judice or where
court action had been determined.

Whilst blame has been laid in a number of cases on the Horizon system for the
financial discrepancies and shortages which have led to subpostmasters
having their contracts terminated and subsequent court action, POL continues
to express full confidence in the integrity and robustness of the Horizon
system.

The Horizon computerized accounting system operates in all post office
branches and has done so for over 10 years, processing up to 750
transactions a second across the country at peak times. The system and the
processes around it offer a very high level of security and resilience and are
designed to ensure that, should part of the system or equipment fail, the
integrity of the accounting records is always maintained. The system has
proved to be very robust since its introduction.

The Horizon system was fully tested at the time of the nationwide
implementation and all new software releases are also subject to rigorous
testing prior to going live in order to assure the accuracy of the accounting
processes. For example, the testing for the latest upgrade to the system
introduced over the past year was independently assured by Wipro as being
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‘pest practice’ (Wipro is amongst the largest global IT services companies in
the world and recognised experts for Product Engineering and Testing).

As regards ongoing performance, the Horizon information security
management systems are accredited to industry standards and there are
extensive controls to ensure data validation and reconciliation. A transaction
log is available for every branch and full audit logs of all system and user
activity and transactions are securely sealed, backed up and retained to
provide an evidential and investigative repository.

The system is based on the principles of ‘double entry book keeping.’ If an
accounting issue is identified at a particular branch (which may have been
caused by, for example, incorrect keying of a transaction by the
subpostmaster), there are full processes in place between POL’s central
accounting team and the individual subpostmaster to investigate and resolve
such issues and identify the responsibility. It is important to note that these are
the kinds of issues that can occur in all businesses (incorrect data entries by
branch staff, incorrect amounts of cash taken etc). These are user issues and
are not examples of the Horizon system itself creating errors.

All subpostmasters and branch managers are able to utilize the reporting
functions within Horizon and to perform counts of their cash and stock in order
to confirm their accounting position on a timely basis.

EDWARD DAVEY