Summary linked, long version here: https://www.jfsa.org.uk/uploads/5/4/3/1/54312921/origins_of_a_disaster_-_summary_-_eleanor_shaikh.pdf

Both hosted by jfsa.org.uk, the Justice for Subpostmasters Alliance website.

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. In any event, they argued they would need months to assess his chosen solution:

‘POCL believe that the hardware and software is probably sub-optimal as the platform for providing network banking and Modern Government services, but would need several months' work to have a clear view.'