For five years Moira Bowman carried out her calculated thefts by inventing till receipts for non existent returns.

Her secret was finally uncovered through an internal investigation at the EH Booth branch in Carnforth, Lancs. A covert camera over a supervisor's cabin - nicknamed the Sin Bin - filmed her carrying out her thieving.

The 58 years old mum of Grosvenor Place, Carnforth was jailed for three years by a judge at Preston Crown Court who said the full amount she took may never been fully known. It worked out at more than £1,000 every week for five years.

She had pleaded guilty to theft and money laundering. The prosecution said the stolen cash totalled at least £350,000.

Jail terms were also handed down to her two sons who had been convicted of money laundering following trial. Ian Bowman, a 35 year old father of eight, of Wentworth Crescent, Morecambe was given 21 months prison and his 33 year old brother Mark Bowman of Burdock Walk, Morecambe received a 15 month term.

They had claimed in their defence they believed the money had come from their mother's savings and also family inheritances.

Their mother carried out her theft between July 2001 and September 2006, while a customer services supervisor, having worked for the company for many years.

Her net earnings during her last year at work were £12,500. It was not until September 2006 that the head of loss prevention security at Booth's carried out an investigation into the Carnforth branch. It had been noted there had been an abnormally large volume of so called open key refunds. Such refunds were given to customers who returned unwanted goods bought in the store and the only staff allowed to give them were supervisors and those above them.

It would operate by a key being used to open a till, goods scanned for their bar codes and receipts printed. The receipts would then be put in the supervisor's cabin, a place known as the Sin Bin.

Some returnable goods, like fresh food produce, some newspapers and wine, did not have bar codes. Moira Bowman had complete control over the tills, enabling her to manipulate entries and steal money, said Mr Kennedy.

On one particular day, she had used the system to steal around £500.

The cash stolen was mainly banked in four of her accounts. Sums went on to be paid into her sons' accounts. Ian Bowman benefited to the tune of over £162,000 and his brother, more than £84,000.

After losing his job, Ian Bowman set up his own IT firm called Search First Direct, using his mother's stolen cash. Money also went into his mortgage account.

Mark Bowman used stolen cash to support himself after losing his employment.