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A freedom of information request found that the Crown Office was told of possible problems in May 2013.

The Crown Office said that it aimed to ensure “all miscarriages of justice resulting from unreliable evidence obtained from the Horizon system are identified and overturned”.

Deputy crown agent Kenny Donnelly said: “COPFS estimates up to 100 Scottish cases may be affected. This is lower than in England and Wales due to COPFS policy decisions made in response to awareness of the Horizon system issues, and the fact that all cases in Scotland were prosecuted by the procurator fiscal under the application of Scots criminal law.”

Kenny MacAskill, who was justice secretary when the Crown Office first became aware of issues, said he had “no recollections” [sic] of discussions with prosecutors or the lord advocate.

He told BBC Scotland News: “In the ether people were aware of issues, but matters were still proceeding and it was, to some extent, under the radar.

“I’m sure Crown officials would not ever seek to prosecute somebody who they knew to be innocent but we need to be assured that they started to make inquiries [into the concerns].”

Dr Andrew Tickell, senior law lecturer at Glasgow Caledonian University, told BBC Scotland’s The Nine: “The revelation that the Crown Office knew of problems is huge. Did they stop prosecuting? Did it occur to them that any of their cases before 2013 might now be unsafe because of these uncertainties?

“At the moment we know less about the Scottish dimensions of this scandal than we do about the rest of the UK.”

It was confirmed yesterday that Paula Vennells, who led the Post Office between 2012 and 2019, is to hand her CBE back “with immediate effect”.