A member of the public intervened when they saw a man ripping the back number plate off a car in Quendon on September 10.
The man was seen taking the plate from a black Audi A3 in Cambridge Road at around 5.15pm and after being challenged by the passerby, he dropped the plate and made off down the street before getting into a white Vauxhall Astra.
Number plates from two other vehicles in Newport were also stolen between 5pm and 5.40pm on September 10.
The cars - a grey Mini Cooper S and a silver Mercedes - were both parked in High Street, Newport and the total value of the theft is around £80.
Essex Police have since released an image of a man they would like to speak to in connection with the incidents.
Anyone with information pertaining to the image should contact PS Scott at Saffron Walden police station.
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