Engine cutting out

I purchased a car 18 month ago, it ran fine for a year, then driving back from Paris the engine light came on, the rev counter dropped to zero and the engine cut out. The only way to restart the engine is to dip the clutch whilst rolling, turn the ignition off completely and restart as normal. The engine light then goes off and the rev counter goes to normal. The car will drive as normal, sometimes for a few miles, or sometimes only for a few yards and then the same problem happens again. It seems worse when the weather is hot.