New figures measuring ambulance trust performance against a set of key clinical practices has exposed huge variation in care for stroke.

The first data set for the clinical indicators, which were introduced in April this year, show the proportion of patients suspected of having a stroke who were conveyed to  a specialist stroke unit within 60 minutes ranged from 46.6 per cent in the East Of England to 90 per cent in the North East.

London achieved the indicator 64 per cent of the time, slightly below the national average of 66 per cent, despite the easier availability of hyperacute stroke units in the capital.

A spokesman for London Ambulance Service said the data included patients whose symptoms had begun hours before the ambulance service was called, so they were not conveyed under a blue light and therefore did not arrive within 60 minutes.

He said the service would be reviewing how it recorded its data over the next few months.

National Institute for Health and Clinical Excellence guidelines recommend all stroke patients are taken to a specialist unit as soon as possible to improve outcomes.

A spokeswoman for the East of England Ambulance Service admitted its performance on stroke was “disappointing”, but said it was working hard to educate staff and was “confident” this would lead to improvements.

The indicators also measure the proportion of heart attack patients receiving primary angioplasty within 150 minutes; cardiac arrest survival rates and the proportion of cardiac arrest patients who are resuscitated by ambulance staff.

On average, the proportion of patients receiving angioplasty within 150 minutes was 90.8 per cent, ranging from 82.3 per cent in the area covered by North West Ambulance Service to 97.7 per cent at Great Western Ambulance Service.

Announcing the first publication of the data, health secretary Andrew Lansley said he expected ambulance trusts and the wider NHS to use the data to shape improvements.