since the first incident

The first incident was before it was rolled out.

Driven by wider political agendas which included the protection of Japanese inward investment in UK plc, Blair ruled that the Post Office must purchase a salvaged version of Horizon. Insufficient work had been done to determine the viability of this option and the Post Office itself was adamantly opposed to the idea. Right up until the day before the Prime Minister’s decision, the Post Office were vociferous; they wished to terminate Horizon and start afresh with a new supplier.

The report, and a summary which I've taken that quote from, are hosted on the JFSA website:

After many months of detailed research, long-time supporter of the Subpostmaster campaign, Eleanor Shaikh, has very kindly allowed her recently completed report into the early history of how Post Office's flawed Horizon computer system came into existence to be made available from the JFSA website.

At almost 600 pages, 'Origins of a Disaster' gives an in depth analysis of the discussions and decisions taken from 1998-2000, heavily referencing Government documents, naming all those involved and the 'hands on' approach adopted by the Prime Minister Tony Blair at the time the final decision to proceed was taken.

Eleanor has also produced a six page summary of her report which she has made available.

They will no doubt prosecute some tiny fish doing the bidding of the sharks who paid their salaries. They're not going to touch the real villains.