Its analysis of the four health systems in the UK found that England had fewer staff per head but delivered higher levels of activity, crude productivity of its staff and lower waiting times.

It found Scotland had the highest levels of poor health, the highest rates of expenditure, the highest rates of hospital doctors, GPs and nurses per capita, and yet it has the lowest rates of crude productivity of its staff in 2006/7.

The performance of Wales and Northern Ireland in key measures of waiting has been poor compared with England.

Dr Jennifer Dixon, director of The Nuffield Trust, said: ‘We believe the research raises important questions about the efficiency of care across the devolved nations.'

Scotland's health secretary Nicola Sturgeon said: ‘The 2006 figures overestimate the numbers of doctors by 27% due to Nuffield including general dental practitioners for Scotland but not for other parts of the UK. While 2006 predates the current Scottish Government's period in office, it is nevertheless important to defend the reputation of the NHS in Scotland when inaccurate claims are made.'

‘The current performance of our health service is far better now than in 2006 but it transpires that the productivity of the NHS in 2006 was also better than claimed in this report.'