In May, I was surprised to receive a letter from Post Office Ltd informing me of its Historical Shortfall Scheme.

It stated that this is a scheme to independently assess applications from postmasters who believe they have experienced shortfalls related to the previous version of its Horizon system. The scheme is open until 14 August.

I was a subpostmaster from 2004 for seven and half years and had few worries about the Horizon system. The concerns that I did have were around the lack of transparency of the system that made investigating discrepancies a significant challenge.

As a retailer with decades of experience investigating shop cash register audit rolls, the nature of the Horizon transaction record was in a totally different manner.

I experienced a shortfall on the last balance that I undertook as subpostmaster on the day before I handed the office over to my successor. It was a few hundred pounds and because of the very limited time to investigate I made good from my own money to enable the handover to be undertaken on schedule with the correct stock and cash witnessed by a Post Office auditor.

That was in September 2011 and, while all the other issues that needed to be dealt with after selling my business are long in the past, the shortfall from that final balance has remained an irritation.

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Almost nine years on from resigning as subpostmaster I have limited physical evidence of the shortfall, but I can recall the incident from memory in good detail. After drafting a set of answers to the 31 questions that the application form asks I felt that it would be useful to get advice from both the National Federation of SubPostmasters (NFSP) and the NFRN as I was a member of both.

Sharon Merryweather at the NFSP talked me through the process that Post Office Ltd has set up to bring resolution to current and former postmasters and postmistresses who feel that they suffered shortfalls due to the Horizon system. She emphasised that Post Office Ltd is taking a pragmatic approach to resolving the cases reported to the scheme.

She added that the Independent Advisory Panel, which includes a forensic accountant and a retail expert, are independent from Post Office Ltd. The panel will be able to ask Post Office Ltd for evidence from its archive.

When I spoke to the NFRN helpline they gave me contact details for Post Office support service Subpostmaster and one of their advisors, a former Post Office Ltd auditor, who gave me practical advice on how to frame the issues that I told her about. She also reminded me of the some of the day-to-day terms and support that was available to me as a subpostmaster.

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Both Subpostmaster and the NFSP said that although I have limited paper evidence from events of September 2011, I should not see this as a handicap in making an application. Both are aware of applications for thousands of pounds being made with no supporting proof.

I will certainly be making an application to the Post Office Historical Shortfall Scheme by the closing date of midnight on 14 August in the hope that it will bring resolution to my irritating memory. If you had an unresolved shortfall when you were running a Post Office using the previous version of Horizon, make sure you get your application in before the deadline.

It doesn’t matter how small the shortfall was, this is your opportunity to get it considered by the Independent Advisory Panel.