A SENIOR Notts Police officer is to challenge a speeding charge in court by claiming the radar gun used by officers from her own force did not give an accurate reading.

Superintendent Helen Chamberlain was allegedly clocked driving at 79mph on a stretch of the A6097 Epperstone bypass between Epperstone and Oxton where the limit is 50mph.

She was originally given a verbal warning by the officer who stopped her, but a more senior officer later disagreed and asked the Crown Prosecution Service to review the case.

Superintendent Chamberlain, 43, from Harworth, who works for Notts Police City Division, now faces a charge of speeding.

She has pleaded not guilty at Nottingham Magistrates' Court.

Ian Boddy, defending, told District Judge Morris Cooper that the basis of the not-guilty plea was over doubts about the accuracy of the speed-gun test result, the quality of traffic signs on the A6097 Epperstone bypass and the process that led to the decision to overrule the initial warning.

Eight witnesses, including Superintendent Chamberlain, were set to be called at her trial in October.

Brian Gunn, prosecuting, said that a defence partly based on the accuracy of the equipment used to record the speed of Mrs Chamberlain's vehicle would now lead to the need for expert technical witnesses.

He added: "I would want to, under cross-examination, ask the defendant why she did not challenge this at the time."

Mrs Chamberlain was released on unconditional bail prior to her scheduled day-long trial at the same court on October 29. The Post understands she has not been suspended.

Notts Police served notices of intended prosecution on 47,320 alleged speeders in 2009. This included alleged speeders caught on fixed and mobile cameras and speed gun devices used during police enforcement operations.