It happened on Tuesday when the 39-year-old victim was making a delivery to a property in Rickmansworth Lane, close to the junction with Ravensmead, Chalfont St Peter. As he was returning to his van he saw a man walking towards him with his hands behind his back. The man spoke to him and pulled out a flick knife. The man then ran to the driver’s side of the delivery van, got in and drove away. The offender is described as white, aged approximately 35 to 45 years old, around 6ft tall, of large muscular build, with a square shaped face. He had light brown hair which was shaved on the back and sides, and short and spikey on the top. He was wearing a plain light grey jumper and dark coloured trousers.