The names of four postmasters with addresses in Oldham who were prosecuted and sued the Post Office in a high court lawsuit have been leaked in a major data breach.

The Post Office says it has launched an urgent investigation and referred itself to the data watchdog, the Information Commissioner's Office, after it published the names and addresses of hundreds of post office operators on its corporate website earlier this week.

More than 700 sub-postmasters were wrongly prosecuted for theft during the Horizon IT scandal between 1999 and 2015, due to incorrect accounting software which made it appear as though money was missing at their branches.

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Now, the names and addresses of more than 500 who were involved in suing the Post Office in a high court lawsuit in 2017 have been revealed in the leaked document.

These include the details of four people with Oldham addresses.

The confidential settlement deed in the ‘Alan Bates and others -v- Post Office Limited’ action, dated December 10, 2019, reveals the Post Office paid out £15m in respect of legal costs and disbursements, £42m by way of damages and litigation funding and a further £0.75m in 'support fund costs' - totalling £58 million.

Former sub-postmaster, Christopher Head from Tyne and Wear, who has been an avid campaigner in the fight for justice amid the Post Office scandal, said he sent an email to Post Office bosses, chief executive Nick Read and Chair Nigel Railton, regarding the data breach.

In a post published on X, Mr Head pointed out that the document "was to be confidential", as per clause 12 of the agreement.

The former postmaster said many of those named in the document "hadn't shared details with their own families", adding that many are "extremely traumatised by this whole scandal even today and this has further impacted them". 

A Post Office spokesperson said: “The document in question has been removed from our website.

“We are investigating as an urgent priority how it came to be published. We are in the process of notifying the Information Commissioner’s Office (ICO) of the incident, in line with our regulatory requirements.”

An ICO spokesperson said: “Post Office Limited have made us aware of an incident and we are assessing the information provided."

Hundreds of victims are awaiting compensation despite the Government announcing that those who have had convictions quashed are eligible for £600,000 payouts.

In 2017, legal action was launched against the Post Office by sub-postmasters.

Two years later, a High Court judge ruled that Horizon contained a number of “bugs, errors and defects” and there was a “material risk” that shortfalls in Post Office branch accounts were caused by the system.

The Post Office agreed to pay out £58 million to them. 

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