Kim Roberts, 59, has been sentenced for three years for stealing antiques and paintings valued at over half a million pounds from her former employer’s home in Cirencester.

Roberts had been personal assistant and housekeeper to Gloria, the Dowager Countess of Bathurst since 2013. The Countess was alerted to the thefts after Roberts approached Michael MacDonald, an antiques dealer, about a Ben Nicholson painting worth £200,000, that she was wanting to sell privately.

MacDonald became suspicious after she told conflicting stories about how she had acquired the painting. He contacted Lefevre Fine Arts, who had sold the painting in the past, who alerted Lady Bathurst.

When the Countess realised it was missing she discovered that other items, including a Picasso sketch, had also gone.

Roberts was arrested at Lansdowne Club in Mayfair where she had arranged to meet with another art dealer. A set of keys to Lady Bathurst’s London flat were also found in her possession.

The court heard that Roberts had also stolen a car from the home of a previous employer in October 2012.

When initially questioned she claimed that she had been given the two artworks as a gift.

The Judge praised the ‘integrity and professionalism’ of the art dealers involved in the case.

Jailing Roberts, the Judge said: ‘These were premeditated offences by you as an employee with the clearest intention of selling the items on.

‘There is a greedy and calculated nature to your offending. What you did in effect was to repay your employer’s trust with avarice and dishonesty.

‘Lady Bathurst is a wealthy woman from a wealthy family and you no doubt thought she could easily bear the loss, even if she did discover it. The fact she is wealthy is not a mitigating factor. The criminal justice system should protect all, whether prince or pauper.’