The Post Office has launched an external review into the Horizon computer system at the centre of its legal dispute with sub-postmasters.
Some sub-postmasters blame the Horizon system for what they claim are false accusations made against them, over accounting discrepancies.
Thousands of Post Offices use the Horizon IT system for their accounts. Postmasters claim faults with the technology could be generating unexplained losses.
The Post Office has consistently denied this. In recent years, dozens of postmasters have been charged and even jailed for accounting shortfalls.
Others have had to make up cash discrepancies following prosecutions. Post Offices have been forced to close.
In 2009 Computer Weekly, which has followed the story closely, interviewed some of those affected. The sub-postmasters related stories of bankruptcy, prosecution and disrupted livelihoods.
In February that year Access Legal, the consumer arm of law firm Shoosmiths, launch the action for a group of six postmasters.
A spokesman at Access Legal said an external investigation was a good way forward.
While it has full confidence in the Horizon system, the Post Office has agreed to an external review after MPs applied pressure for an external investigation.
A Post Office spokesman said: “The Post Office continues to have absolute confidence in the robustness and integrity of its branch accounting processes.
"Over the past 10 years, many millions of branch reconciliations have been carried out with transactions and balances accurately recorded by more than 25,000 different sub-postmasters.
"The Post Office has no hesitation in agreeing to an external review of these few individual cases that have been raised with us by a number of MPs.”