The inquiry is pausing now for a short break until 11:55

We'll be bringing you more updates from Aldwych House when it returns, so stay with us.

We've been hearing excerpts from several letters between Bates and the Post Office in the months leading up to and at the time of his termination.

Bates says the final letter terminating his contract gave him no reason for the termination and he was never provided with any other explanation.

Asked how the letter made him feel, he says: "I was annoyed with them, to put it mildly, but I think it was partly expected in a way, because it was pretty obvious that they were after me one way or another.

"The build-up of correspondence over the period was certainly pointing in that direction."

Bates adds: "They just decided, I felt, they were going to make a lesson of my case, because a number of other people knew what was going on at that time.

"I think... the Post Office liked to try and give lessons of how they were in charge."

Image source, Post Office inquiry

Sam Hancock
Reporting from the inquiry

The focus of these evidential hearings tends to be documents - letters and emails written by or sent to the person giving evidence, their witness statement, official forms, that kind of thing.

Here in the inquiry room, journalists and members of the public often screenshot them when they appear on screens dotted around. (Anyone reading our live page can do the same by tapping the Play button at the top and following the hearing live.)

So far, we've been shown a variety of such documents that illustrate Alan Bates' struggle to get anyone at the Post Office to help him after he found issues with the Horizon system.

In one lengthy letter Bates sent in 2001 to a senior member of Post Office staff, he explains his situation in detail - that money is showing as missing from his branch but he believes this is down to a fault with the Horizon IT system. At the end, he asks: "What should I do?"

Asked by inquiry lawyer Jason Beer if he ever received a response to that letter, Bates replies: "Never". It's fair to say there's a palpable silence in the room at this point.

Earlier Jason Beer KC, lead counsel for the inquiry, began the session by saying the Post Office's "late and problematic disclosure of documents" has been repeated throughout the inquiry.

He describes the late disclosures as "highly disruptive".

Beer says after the write off, there continued to be some shortfalls shown on Horizon.

Bates says it was also "overs", or surpluses, as well as "unders".

He says there was a claim at the end of his contract that his office owed around £12,000 to £14,000.

Bates explains that when they undertook their weekly balance, staff were meant to put in money to make up the figure or take money out if it was over, which he says he refused to do.

"I rolled through the shortages or the overs each time so it had a running total," he says.

This is because he "really did not know what the office was up to", he says.

Bates says he never reset the system and Post Office was aware of what he was doing.

Now Beer turns to another letter Bates sent on 7 January 2002.

In the letter, Bates says the cash account for his office was still showing £1041.81 in the suspense account, and that he has no doubt that this was due to errors in the Horizon system.

He also says he gave more detail in previous letters to his retail manager, which he didn't receive a reply to.

Bates writes that enough time had passed for Post Office Limited to have resolved the issue, and allowing the issue to drag on was causing stress and strain and cast doubt over his honesty.

Beer then turns to Bates' inquiry witness statement, where he says by 6 March 2002, he was notified that the Post Office did not plan to take further action and would write off the amount.

The inquiry now looks at a Loss Authorisation form, which confirms a voucher would be sent to Bates to clear the amount.

Inquiry lawyer Jason Beer is now pulling up one of the first letters that Bates sent to the Post Office, after balancing issues emerged in his office after Horizon was added to his branch.

Beer reads out the letter, where Bates writes about the shortages and says that he is unsure where it comes from. The letter outlines the shortfalls in Bates's branch and says that he believes Horizon is at fault.

He asks what he should do at the end of the letter but when asked, Bates says that he never got a reply to it.

Beer is asking about the period in late 2000 when the Horizon system in Bates's Post Office first started showing unexplained shortfalls.

Bates confirms a section from his witness statement in which he says that, on one day in December that year, he contacted the helpline seven times, with one call lasting an hour.

Asked whether they were able to help, Bates says: "Not really. Stating the bleeding obvious, I think, really is one description I might use."

Beer notes that Post Office records showed that, between December 2000 and November 2003, when his contract was terminated, Bates and his assistants made 507 calls to the helpline, of which 85 related to Horizon.

Bates adds that "often we never bothered ringing" the line because it proved so unhelpful.

Image source, Post Office Inquiry

Bates is asked now about the introduction of the Horizon system to his Post Office branch.

In his written evidence, shown on screen, Bates recalls Horizon being installed from 2 October 2000 and says that he had no involvement in discussions to adopt the software.

Bates says he did not expect the system to find "apparent discrepancies" he would not be able to "identify the cause of and resolve", or discrepancies the Post Office would try to hold him liable for without the cause being investigated.

Beer asks Bates what he means by that.

Bates says he expected to be able to track down any transaction that he or his staff had undertaken himself at the branch.

He thought the system would enable him to do that. In previous roles, he used software that would allow him to extract information like that.

Bates says there was very little flexibility in Horizon for reports he could control the search parameters for.

Beer says this was a constant theme Bates pursued with the Horizon system.

Sam Hancock
Reporting from the inquiry

It's worth unpicking what Alan Bates made light of at the beginning of his evidence.

Going through some of his particulars, inquiry lawyer Jason Beer suggested Bates was a sub-postmaster for a "relatively short period of time", to which Bates said "that was due to the Post Office, not to myself".

There were laughs around the room, including from Bates, who seems as comfortable as ever giving evidence today.

As a reminder, Bates took over a shop in a town in north Wales - which had a Post Office counter in it - in 1998. In 2000, just after he had Horizon installed, he noticed there was a shortfall of around £6,000 on his books due to so-called Giro deposits. In 2003 his contract was terminated by the Post Office because there remained more than £1,000 unaccounted for and he refused to accept liability.

Bates and his partner Suzanne Sercombe kept their shop but lost the PO counter, and their investment of around £60,000 along with it.

He's since relentlessly campaigned for justice, not only for himself but the hundreds of postal workers prosecuted between 1999 and 2015.

Beer continues by asking Bates about his reasons for wanting to become a sub-postmaster.

He shows the inquiry an excerpt from Bates's witness statement in which he says a "key attraction" of working at the Post Office was that it would "provide secure employment" because it "provides a community service and has an established brand in the community".

Image source, Post Office inquiry

Alan Bates says that he was seeking redress for a group of people when he started his individual campaign.

"Once I started that, I found others along the way and eventually we all joined up," he explains.

Inquiry lawyer Jason Beer quotes what Bates said back at the time, that he "dedicated this part of my life to this cause". Bates adds it was also because of "stubbornness".

"Once you saw the harm and injustice descending upon all those people, it was something you felt you had to deal with, something you couldn't put down," he says. "You had to support the rest of the group."

Bates is asked now about his time as a sub-postmaster between 31 March 1998 to 5 November 2003.

Beer says by comparison with other sub-postmasters, five years is a relatively short period in the role.

Bates agrees, but says that's "due to the Post Office, not to myself".

Beer puts it to him that Bates has spent more than four times that period campaigning.

"Oh yes," Bates says.

Bates goes on to say that the Post Office terminated his contract and gave him three months notice with no reason for doing so.

Bates says he thinks this is because of issues he raised over the Horizon system based on faults he discovered over the years.

Beer opens by asking Bates about his background, his work before becoming a sub-postmaster, and how he became familiar with the development of computer science.

Bates confirms that, for 12 years, he worked in heritage and leisure project management, in the process becoming familiar with various types of sales software.

Beer asks him to what extent that background helped him when he became a sub-postmaster and, later, had to work with the Horizon system.

Bates says that, when Horizon first came in, he was "quite positive about it", but that he later found it "frustrating" because of "many shortcomings in the system".

Sam Hancock
Reporting from the inquiry

That was quite something.

Inquiry lawyer Jason Beer KC kicked off today's hearing by calling out the Post Office for its "late and problematic disclosure of documents".

It's been "highly disruptive" and a "constant theme in this inquiry", we've been told.

At the point Beer disclosed that since 2 February alone, the Post Office has handed over 73,720 documents, I saw more than one person in the inquiry room turn to the person next to them and either say something under their breath or shake their head.

Some of the documents, after all, were emails between Post Office executives and their personal assistants.

It's the first time a hearing I've been to has begun this way but we've been assured by the inquiry's chair Sir Wyn Williams that proceedings won't be adjourned or delayed, despite the issues Beer raised.

Image source, Post Office inquiry

Now for the main event.

Alan Bates, the campaigning former sub-postmaster, has now being sworn in as he prepares to begin his evidence.

We'll be providing live updates here, but you can also watch the events in Aldwych House by clicking Play at the top of this page.

After Beer finishes his speech Sir Wyn Williams now says were going to carry on with the inquiry without a delay for disclosure issues to be dealt with.

He says he does not want to hear from core participants on the matter.

"I have to exercise judgment and come to a balanced decisions. My intention is continue with the evidence sessions in accordance with the published timetable so far as it is reasonably possible," Williams adds.

This means some witnesses may need to be recalled, he says, which he says is "undesirable".

Sir Wyn accepts he may be to blame for some of the disclosure issues as he says some of the timetables he set for hearing evidence might be a bit tight.

But he says it is his belief the inquiry should not last a day longer than necessary.

Beer is giving a run down of some of the more technical issues with disclosure of documents related to the Post Office inquiry.

He says the matters the inquiry is investigating span two decades.

To proceed with hearings, the inquiry has had to prioritise its disclosure to core participants, he says.

Beer adds that there may be a need to recall some witnesses to ask questions about documents that had not been processed in time to ask them questions about them in the coming weeks.

Stay with us as we bring you more detail as we get it.

Beer is still speaking. He describes the late disclosures from the Post Office as "highly disruptive".

He says that, in order to prevent future disclosure issues, the inquiry provided the Post Office with a series of deadlines for any further late disclosures. In particular, he said the Post Office was told that any disclosure had to be provided by the Post Office no later than six weeks before an oral witness was due to give evidence.

Beer says the inquiry legal team "ought to continue to monitor the Post Office's compliance" with the disclosure requirements and report to the chair at regular intervals.

In legal terms, disclosure is the sharing of documents or material which may be relevant to a case between the parties.

Image source, Post Office inquiry

We are getting under way with inquiry chair Sir Wyn Williams speaking first.

He says he understands that before hearing evidence, Jason Beer KC - lead counsel for the inquiry - wishes to raise an issue of disclosure.

Beer says the core participants were sent an email from the solicitor to the inquiry that contained correspondence from the Post Office.

He says the Post Office's "late and problematic" disclosure of documents has been a consistent theme throughout the inquiry.