Former Fujitsu software engineer Gareth Jenkins has said he gave evidence in the prosecution of former sub-postmasters based on “informal chats”.
Mr Jenkins had testified that “remote access” to sub-postmaster computers was not possible when in fact it was – something that may have undermined their defence in court.
Between 1999 and 2015 more than 700 sub-postmasters were prosecuted for fraud and theft by the Post Office based on faulty data from Fujitsu’s Horizon accounting system.
Mr Jenkins, who helped to develop the system, was being questioned for a second day at an inquiry into the scandal.
On Tuesday he apologised for his role in the wrongful conviction of a subpostmistress who was jailed for theft when she was eight weeks pregnant.
However, Seema Misra told the BBC that the statement from Mr Jenkins was “too little, too late”.
At the inquiry on Wednesday, lead counsel Jason Beer asked Mr Jenkins a series of questions about how much he knew about Fujitsu’s ability to remotely access sub-postmaster computers.
In its prosecutions, the Post Office had argued that Horizon could not be accessed remotely by any other party.
This showed that accused subpostmasters must have been responsible for the shortfalls in their accounts, it said.
But this turned out to be untrue, depriving those accused of an important line of defence.
Remote access was not only possible by Fujitsu’s engineers, it could be done without leaving any trace, in a way that was indistinguishable from changes made by subpostmasters.
Mr Jenkins told Mr Beer he had only found this out in 2018.
