A senior police officer is to be sentenced today at Winchester Crown Court after she was convicted of an ''extensive range of petty retail frauds'' targeting a number of High Street stores.

Tanya Brookes was a chief inspector at Surrey Police when she carried out the scams netting hundreds of pounds against several household names including The White Company, Micro Scooters and Boots.

The 46-year-old mother-of-four, who worked under her maiden name of Sillett, pleaded guilty at Winchester Crown Court to five charges of fraud by false representation and three of making an article used in fraud.

A further five offences which she denied were ordered to lie on file. A further two charges of acting with intent to prejudice/defraud HM Revenue and Customs which were due to be heard at a third trial will also now lie on file.

Brookes, of Nursery Road, Godalming, Surrey, was also previously found guilty following a trial of nine offences of making an article used in fraud, 14 of fraud and two of converting criminal property. She was found not guilty of a further two offences.

Nicholas Tucker, prosecuting, said at the start of the first trial how Brookes, who was also married to another senior police officer, David, had joined the Surrey force as a university graduate and he described her as a ''high-flyer''.

He said that it was as she was about to mark her 20 years' service in July 2011 that she became the subject of an investigation by her own force.

Mr Tucker said: ''It is our case that despite the healthy salaries which she and her husband enjoyed as senior police officers, Mrs Brookes - for reasons which may remain a mystery - expended an extraordinary amount of effort and her own time devising various scams, principally targeted against High Street retailers.

''To compound matters, we say that on occasion she exploited her status as a police officer in order to inspire trust in individuals she meant to deceive.''

Mr Tucker explained that one of Brookes' main targets was The White Company. He said that she would buy items such as Poitier cotton sheets or a cashmere satin-edge blanket from the chain's outlet store in Bicester, Oxfordshire, at a discount rate.

She would then falsify a bank statement on her computer showing that the full price for the product had been paid and return it to another branch of the store and fraudulently reclaim the difference in price. She would tell shop staff that the items had been bought by ''an extravagant great aunt''.

Mr Tucker continued: ''Mrs Brookes would often be wearing her police ID on a lanyard round her neck - this was irregular, and the prosecution say it was a ploy by Mrs Brookes to capitalise on the trust people tend to place in police officers.''

In another ''scam'' outlined by the prosecution, Brookes offered to organise a stall selling Micro Scooters at her son's nursery. Mr Tucker said that despite the fact that the parent-teacher association decided to decline her suggestion, Brookes went ahead anyway and when she received the two promotional scooters offered by the manufacturer, she returned them to the Kingston branch of John Lewis and exchanged them for vouchers and a different Micro Scooter.

Mr Tucker described another fraud which involved Brookes buying products such as Sculptinex facial treatments, Clearblue fertility monitors and Medela breast pumps in bulk and at discount on eBay and returning them to Boots to claim the difference in price.

She also bought forged discount vouchers for products such as Lurpak butter on the internet and used them to buy products at reduced price in stores such as Waitrose, Mr Tucker said.

Following the hearing, assistant chief constable Gavin Stephens, of Surrey Police, said: ''We expect the highest standards of conduct from all of our employees and this kind of behaviour has no place in Surrey Police.

''The vast majority of our officers and staff who serve the people of this county are professional and hard-working and the public rightly trust them to act with integrity at all times.

''We will not hesitate to thoroughly investigate any evidence of wrong-doing and take swift action if any officer is involved in criminality.

''This was a complex investigation but thanks to the painstaking work of the officers involved, the scale of offending behaviour by Tanya Brookes was uncovered and she has been brought to justice.

''The force immediately referred this matter to the Independent Police Complaints Commission (IPCC) when it came to light and Brookes was subsequently fast tracked through our disciplinary procedure and dismissed from her job.

''Our action in this case demonstrates that Surrey Police continues to hold itself and its employees to account at all times.''

In November 2012, Brookes appeared before a fast-track gross misconduct hearing and was dismissed without notice from Surrey Police.