I guess this is the bit I didn't really understand. How did it go for so long without anyone working it out?
Essentially you have three data points that need to balance.
1- Your takings (Cash)
2- Your stock (Stamps etc)
3- Your sales records
For example, in the simplest terms -
You start the week with 10 stamps worth £1 each
You sell 5 stamps
You have £5 at the end of the week.
All is good. What I think was happening, some terminals with dodgy connections were corrupting either the sales or the stock holding (well, one corrupts the other, but one would be the source of the issue)
So it might come out as -
Start with 10 stamps
You sell 5 stamps but the system thinks you sold 7
You have £5.
You're now £2 short and have to put that £2 in yourself.
I realise that's hugely simplified and it's easy for me to sit here saying 'why did no-one run a manual log and see where the money/stock wasn't matching up, but if I was losing a couple of k a week, I'd invest the time, no?
And of course, I'm making out it's the Subpostmasters fault and of course it isn't, and I have every sympathy for them. It just made me wonder how it went on so long with no-one working out where the stock was going?
(**EDIT** Mind you, in the example above, you then still have 2 more stamps than the system, so I guess it can't be as simple as this... but at the same time, something wouldn't add up and it should have been possible to find what it was? I guess the glitch could have recorded sales wrong, but corrected stock holding right.)
I believe it was just the financial record side they kept and not stock specifically. (well they did but on a daily basis it was a cash reconciliation)
Eg you have a till balance of £10, the system thinks you have sold 7 stamps for £7 but really you sold 5 for £5
The system asks you to enter your till balance, you say £15, it says "error!"
You check and you see its says you should have a till balance of £17, you recount and get £15 so you go
*** no disguised swearing *** it, I will say £17
The next day you sell £5 again. The till again gets it wrong, today thinking you sold 8, so you balance is now supposed to be £10+7+8 = £25 according to the system. But you have £10+5+5 = £20
So again you say £25 even though you have £20.
Bear in mind many post offices are actually probably handling a lot of cash.
So now instead of correctly adding the deposit of £100 someone just made, it doubles that.
I suspect by the time most sub postmasters thought oh this isnt going to fix itself the problem was large, and the ability to at least track it was beyond them.
I am sure a decent accountant would have done it, plus many other professions used to accurate data recording, but how many of the sub posties would have had that available.
I would bet as well, someone was recording the number of times a till float was incorrectly entered. That flagged a visit, and when they visited, surprise surprise the till balance was wrong.
The charge of false accounting would be correct, they did lie about the balance. The root cause was of course covered up.
But the court case would be rather simple. Mlord we visited because we had concerns about teh balances, on checking we found there was a significant difference and the had been lying about the till balance, we suspect for many months.
Hard to dig yourself out of that one!