An allegedly faulty IT system could cost the Post Office millions in compensation payouts, after those affected found financial backing for their legal action.
Hundreds of subpostmasters caught up in an IT issue which they say led to false accounting charges are to bring their case to court, having secured funding.
Sky News first reported that more than 550 participants have gained backing from Therium Capital Management, which funds litigation.
The suit will claim that an IT problem at the state-owned Post Office incorrectly showed that some branches were in financial deficit.
As a result, the Justice for Subpostmasters Alliance claims, many subpostmasters lost their jobs and were financially ruined paying back money that had supposedly gone missing from their branches.
Some people were even sent to prison on charges of false accounting or theft.
But the Post Office denies there are issues with the Horizon IT system and has previously said that it will defend the case.