Post Office accidently leaks names of prosecuted sub-postmasters

The data breach was first reported by the Daily Mail, external and led to an angry response from former sub-postmasters, with one telling the paper she was “incandescent”.

Ron Warmington, the forensic investigator whose firm Second Sight was brought in to probe the Horizon system in 2013, told the Mail it was “an extraordinary breach” of confidentiality and “another example of Post Office incompetence”.

The leaked document contained the names of 555 former subpostmasters who sued the Post Office in 2019.

In 2019, the firm agreed to pay them £58m in compensation, but much of the money went on legal fees.

In a statement the Post Office said the document had been removed from its website.

It said: “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 spokesman said: “We have not received a data breach report on this matter. Organisations must notify the ICO within 72 hours of becoming aware of a personal data breach, unless it does not pose a risk to people’s rights and freedoms.”