To elaborate, the
Improvement Notice set out that the ORR considered Chiltern had contravened provisions of the Health and Safety at Work etc. Act, as well as the "ROGS" Regulations. This should go to show how serious of an issue this was considered.
I sympathise a little with Chiltern's position in a way; they had clearly realised prior to the incident that they had problems with their driver management. But the DfT refused to sign off on the changes that were needed to enable them to fix it.
This arguably makes this incident one of the first (near) incidents caused by misdirected DfT cost cutting, even if only indirectly. It's disappointing that the DfT have got off scot free, and I dread to imagine what other skeletons are in the closet in this regard.