A Fujitsu programmer from the time, Richard Roll, who would become a key witness in the sub-postmasters’ high court case against the Post Office in 2019, told the Eye that Horizon was one the company’s few profitable contracts […] “We would have been fined,” said Roll, who worked at the company between 2001 and 2004. “So the incentive was to pretend it [software error] didn’t happen”, while running “a constant rolling programme of patches to fix the bugs”. Fujitsu “would basically tell the Post Office what they wanted to hear”

https://www.private-eye.co.uk/special-reports/justice-lost-in-the-post