Former Post Office head of partnerships Angela van den Bogerd is set to give evidence to the Post Office Inquiry on Thursday.
The inquiry is entering phases five and six, which will examine governance, redress and how the Post Office and others responded to the scandal.
Ms van den Bogerd will begin her evidence at 10am at the inquiry in central London.
She held various roles throughout her 35-year career at the Post Office, starting off as a network change operations manager, then on to head of network services, head of partnerships, director of support services and the director of people and change.
She was appointed as the Post Office’s business improvement director in 2018, but stepped down from the role in 2020.
Coronation Street actress Katherine Kelly played her in the ITV drama Mr Bates vs The Post Office, which first aired on January 1.
Errors in the Post Office’s Horizon IT system meant money appeared to be missing from many branch accounts when, in fact, it was not.
As a result, the government-owned organisation prosecuted more than 700 subpostmasters and handed down criminal convictions between 1999 and 2015.
The scandal represents one of the biggest miscarriages of justice in UK legal history. Since then, the Court of Appeal has quashed the convictions of more than 100 subpostmasters.
Hundreds of subpostmasters are still awaiting compensation despite the Government announcing that those whose convictions have been quashed are eligible for £600,000 payouts.