To date, the public inquiry into the Post Office Horizon IT scandal has heard or received written testimony from more than 500 witnesses over 152 days of hearings, amassing a vast paper mountain of evidence.

What has been exposed has been a litany of cover-ups and poor management, as well as an at-best dysfunctional relationship with supervising government ministers stretching over decades. This is in addition to the many harrowing stories from post office operators the panel has heard.

As the inquiry moves into its last phase this week – the final two months of a process that began on Valentine’s Day in 2022 – Sir Wyn Williams, the former high court judge who chairs it, will hear whether lessons have been learned by examining the current state and culture of the Post Office and whether it has lived up to its commitment to “full and fair compensation”.

Post Office management will be on tenterhooks when the inquiry recommences on Monday, as the findings of two anonymous surveys sent to 16,000 post office operators, calling on them to share their experiences, will be presented as evidence.

The survey was sent to every current operator in the UK as well as those who are part of the various financial redress schemes, many of whom have been vocal about the problems of securing compensation.

The Post Office is taking this survey of its present-day activities so seriously that the outgoing chief executive, Nick Read, temporarily stepped back from running the company to prepare. He is due to appear before the inquiry for three days of questioning in early October.

Read – who was brought in to replace Paula Vennells and clean up the organisation after the landmark 2019 court victory by 555 post office operators led by Alan Bates – pledged to overhaul the Post Office and “right the wrongs of the past”.

However, he also became embroiled in a reputational crisis of his own: the organisation’s former chief people officer, Jane Davies, said that Read had repeatedly demanded pay increases from the government in an “obsession” with remuneration, and has previously accused him of bullying. An investigation by an independent barrister cleared Read on all counts of misconduct.

The inquiry will also learn whether there has been effective change at board level, where directors repeatedly failed to inquire or take action regarding the Horizon IT scandal and management’s relentless pursuit and wrongful prosecution of more than 700 operators between 1999 and 2015.

As part of a move to repair relations and improve oversight, the Post Office appointed two post office operators as non-executive directors for the first time in 2021. The two directors, Saf Ismail and Elliot Jacobs, will give testimony over the first two days of the inquiry this week.

The inquiry will also delve into the strained relations between the Post Office and the government when the organisation’s former chair, Henry Staunton, appears early next month.

In January, Staunton was sacked by the former business secretary Kemi Badenoch, and a month later went on to accuse the government of wanting to delay compensation for post office operators until after the election.

Badenoch is due to appear in early November, on the same day as Kevin Hollinrake, the former Post Office minister who helped push through unprecedented legislation allowing more than 900 operators to have their convictions overturned after being wrongfully prosecuted.

The final phase of the inquiry, in which more than 30 witnesses will testify, is due to finish in mid-November with two days of evidence from governance experts.

There are growing questions about the longer-term future of the government-owned Post Office and its 11,500 branches across the UK, almost half of which are in rural areas and provide vital services such as banking to communities where banks have closed their branches.

It reported a £76m loss for the year ended March 2023, down from £130m in the previous year.

Nigel Railton, the interim chair of the Post Office, who is due to appear at the inquiry in early October, launched a strategic review looking at the sustainability of the business and its future. Earlier this year, the government held “constructive” talks with unions about mutualisation, which would lead to the ownership transferring from the state to staff.

Williams, chairing the inquiry, has said that his final report will be published “as soon as is reasonably practicable” after the completion of evidence gathering. It is hoped that the report into what has been the worst miscarriage of justice in British legal history will be published by the end of next year.