The woman, aged in her 50s, was walking through Somersall Park, off Somersall Lane, Brookside, Chesterfield, about 5pm, on Saturday, when she was confronted by the flasher.

Pc Adam McGovern said: "The offender politely approached and spoke to the woman twice about the time of day before disappearing and reappearing from a wooded area and exposing himself.

"His victim, who was not physically hurt but was shocked, told the youngster to clear-off and he disappeared into the woods."

The offender was described as white, aged about 16, of slim-build, 5ft 7ins tall, well-spoken, with short, brown hair, a round face and a gold brace on his teeth and was wearing a beige bomber-jacket.

Police told how he exposed himself to the Chesterfield woman while he was in a state of arousal and fled towards Walton Back Lane, Walton.

Pc McGovern added: "We're concerned this youngster could strike again and the type of offending could escalate so we're eager to trace him.

"He was distinctive looking with a gold brace on his top teeth so anyone who may have seen him or knows him are urged to call police as soon as possible."

Witnesses should call Pc 2808 McGovern on 0845 123 3333 or Crimestoppers in confidence on 0800 555 111.

jon. cooper@derbyshiretimes.co.uk