There was a significant discussion after the morning break. Counsel was showing that Young had been engaged in correspondence about a new accounting bug after roll-out. Young pushed back hard, and unsuccessfully tried to pull the wool over the eyes of the Inquiry by claiming that this had been a bug during the pilot phase. This was Young at his most hard-line and least convincing. It then became clear what was at stake. If after roll-out Young was seeing new bugs, then by not bringing them to the attention of his direct report, John Scott, Head of Security, he was enabling the dysfunction that led to wrongful prosecutions of subpostmasters.
I'd suggest that he wasn't seeing new bugs, and more importantly wasn't discussing them with his subordinates, because he didn't want to see them, and was relying on the Ismay Report that they couldn't be seen because it was "known" that they weren't supposed to exist.