Police today praised a mystery man for tackling a knifeman who was robbing a teenage girl.

The Hungarian au pair was walking home from a night class along East Hill, Colchester, at about 8.45pm yesterday when a man held a knife to her chest. He demanded money and grabbed her purse containing £40 cash and a £20 phone card.

But as this happened a passing motorist pulled up in a car.

Det Sgt Roger Napier, of Colchester police, said: "The driver realised all was not well. He jumped out and tackled the robber who was still holding the knife and punched him in the face."

The robber managed to escape with the girl's purse leaving her uninjured but shaken.

Det Sgt Napier said: "Unfortunately, the Good Samaritan did not leave his details. He did offer the girl a lift but she declined. She just wanted to get home and was shocked and frightened at this stage."

The robber is described as aged about 24, 5ft 10ins tall, with dark curly hair and some type of beard. He was wearing wraparound silver sunglasses and a dark coat, jumper and trousers.

Police are appealing for any witnesses, but especially the rescuer, to contact Colchester CID on 01206 762212 or Crimestoppers on 0800 555111

Det Sgt Napier said: "We would like the man who assisted her to come forward so we can thank him and take a statement. Seeing off the robber was particularly brave because you don't know quite what you are getting into in those circumstances."

This robbery is the latest in a series of attacks around the area. A 14-year-old schoolgirl was robbed by a woman in the ladies' toilets at Clacton Railway Station early on Tuesday morning and forced to hand over a small amount of cash.

And police are hunting seven men after four robberies in the past ten days around Braintree. The Bocking Co-op has been robbed twice while Black Notley Post Office and Thomas Cook in Great Dunmow have also been targeted.

Any information on any of the offences ring Crimestoppers on 0800 555111

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