Swollen NHS backlogs could take at least five years to bring under control, the head of the health service has warned.

Speaking on the day the NHS marks its 75th anniversary, Amanda Pritchard, chief executive of the NHS, conceded a number of challenges lay ahead for the health service to provide better outcomes for patients.

After waiting lists surged to a record 7.4 million in April, the NHS was further rocked last month after a damning international study found Britain’s healthcare system has far worse outcomes than almost all of its peers.

Research published by respected think-tank the King’s Fund compared 19 major nations and found the UK severely wanting. Britain’s health service was second worst of all those examined for saving lives, with only the US faring worse.