IANAL. So just looking at this from a layman's point of view.
But what John Bartlett and POL are failing to realise is Horizon is a poison chalice, the bad apple.
Getting a conviction in which the police and CPS need to use Horizon as part of the evidence, they will never get a conviction, especially at trial.
POL can argue till thier blue in the face that the current Horizon system is more or relatively more robust that the previous Horizon, but nobody will believe them.
I've been on jury service before, and I'm thinking about what I would think if I was on the jury where CPS presented Horizon data as part of the evidence.
All the defence has to do is mention "Horizon scandal", "Alan Bates", "All the previous prosecutions that have been overturned", and they have now successfully introduced reasonable doubt in my mind.
I'm.sure there are SPMR who are involved in theft or have commited a criminal act. All professions have them.
The Police definitely has them. My own profession has people who have been convicted of theft.
I think @nauticant has said this before, but POL are never going to get a successful conviction until they get rid of Horizon and have had years of confidence in thier new NBIT system.