Permanent secretary, DH (2010 ranking: 15)

The highest placed woman in the HSJ100, Una O’Brien has steered the department through a year of upheaval. But 2011 will seem an oasis of calm compared with the challenges of 2012.

The department is a quieter place following a wave of redundancies and the departure of hundreds as programmes came to an end. Next year will see the NHS Commissioning Board and Public Health England split from the DH. Their exact form and level of independence from the department is still to be determined and it will be Ms O’Brien’s job to forge the new working relationships essential to making the system work.

Oxford and Harvard educated, Ms O’Brien will be the first DH permanent secretary to have to work with the NHS at arm’s length, throwing up many challenges foreseen and unforeseen. But her communication skills and calm, patient manner make her ideally suited to navigate the choppy seas ahead.

In her third decade at the DH, Ms O’Brien spent time on secondment as director of development and clinical governance at University College London Hospitals Foundation Trust and was secretary to the Bristol inquiry at the turn of the century.