Just one in five have operations to reduce their risk of another potential fatal attack within the two week target set by the National Institute for Health and Clinical Excellence.

A survey of 240 surgeons from 102 hospital trusts across Britain found of 5,513 patients who underwent surgery between December 2005 and December 2007, 83 per cent of whom had a history of stroke, three in 10 waited more than 12 weeks.

The common, procedure called carotid endarterectomy, is routinely used to remove the build up of fatty deposits in the main artery between the heart and brain.

These deposits could cause blood clots that block the blood supply to the brain, leading to strokes.

The average delay from referral to surgery was 40 days. Twenty-nine patients (0.5 per cent) died while in hospital, while 48 (1 per cent) died 30 days after surgery, mainly from strokes.