The collapse of the Tesco trial has put the Serious Fraud Office under scrutiny.
The key witness was Amit Soni, a Tesco senior accountant. He was described as a "whistleblower" who co-commissioned an internal report to expose the gap in the accounts.
The prosecution claimed that when the resulting document landed on the desk of new chief executive Dave Lewis, it was like a hand grenade had gone off in the company.
However, when questioned by the defence, Mr Soni accepted that he had been unaware of improper accounting until he produced his report, which was written months after the problems were already spiralling out of control.
The defence argued that Mr Soni was not a whistleblower at all.
"If Mr Soni didn't know the accounts were unreliable, then how on earth was Mr Bush supposed to know that they were", his barrister, Adrian Darbishire QC, told the jury.