The Labour Party had promised to halt the privatisation programme if it had won power soon enough, but O'Brien beat them to it.
At the Labour party conference in September 1998, the then Secretary of State for Transport and Deputy Prime Minister John Prescott MP announced that he intended to have a 'spring clean of the regulators', and O'Brien immediately offered his resignation.
He had no need to do so, but gained great credit in the railway industry for an honourable offer, which was thought to surprise Prescott.
Prescott intended to set up a new regulatory body for the passenger railway, the Strategic Rail Authority, but he needed legislation to do so.
After announcing that Sir Alastair Morton would become the chairman of the SRA, Prescott needed to find a replacement for O'Brien.