The problem is they still helped prosecute people they knew were probably innocent, and confidentiality causes don't apply in legal cases.

At the very least that's covering up evidence.

Both the Post Office and Fujitsu knew about the bugs before Horizon rolled out. The Post Office did not want it but Tony Blair told them to suck it up, and they did.

The reconfigured Horizon, presented by Ministers in May 1999 as a pristine, state-of-the-art triumph, was in fact the product of a last-ditch, fourth-choice deal in which the Government knowingly accepted a sub-optimal system; it knew Horizon had always been subject to accounting integrity issues, both before and after reconfiguration. But too much was riding on Horizon’s much- delayed rollout; the raft of reforms heralded in the 1999 Post Office White Paper; the credibility of the Modernising Government agenda; the reputation of ICL; ambitions for PFI; and the priceless nerve of Japanese investors. All of these were preconditions which New Labour needed to tease the green shoots of its social and economic renewal.

Once the Prime Minister had made his decision in May 1999, there were to be no more doubts voiced about the system, no more delays or dissent. Inconvenient truths pertaining to its integrity had to be worked around and airbrushed from view. Indeed, the favourable light in which the Government was to present the reconfiguration was one of the few bargaining chips it held for negotiations with ICL/Fujitsu. With the exception of a brief glimpse into the system’s failings which slipped out under cover of parliamentary privilege in 1999, Ministers and officialdom fell into line behind the Government’s sanitised narrative of Horizon.