Ruth Carnall once described herself as “an awful accountant and a good manager” but she has needed both skills to run NHS London for the past three years - probably the hardest job in the NHS.

It is a tumultuous patch where every service reconfiguration is played out in front of the nation’s media and there are deep-rooted problems over the number and location of hospitals, as well as tremendous pressure to make the sums add up. Ms Carnall is seen as a strong leader driving large scale reconfiguration in a difficult environment: this year has seen several prominent chief executives depart. Primary care trusts are now working better with sub-regional leads - a partial answer to the issue of having too many PCTs. Ms Carnall is seen as a big hitter and a close confidant of NHS chief executive David Nicholson.

An NHS veteran, she joined as a trainee accountant in the 1970s and her career has included director of health and social care for the massive southern region.