Judge blasts David Cameron over pro-Nigella comments made to a journalist while fraud trial underway

The judge in the trial of two former personal assistants accused of defrauding Nigella Lawson and Charles Saatchi has issued a rebuke to Prime Minister David Cameron over comments he made about the celebrity chef, urging the jury to reach its verdicts on the evidence alone.

Judge Robin Johnson told jurors in the trial of Elisabetta and Francesca Grillo at Isleworth Crown Court in west London that it was regrettable when public figures commented about someone involved in a trial.

The Grillo sisters are accused of abusing their positions by spending £685,000 on credit cards belonging to the celebrity couple to buy designer goods and luxury holidays for themselves.

Elisabetta Grillo, referred to as Lisa, 41, and sister Francesca, 35, of Kensington Gardens Square, Bayswater, west London, each deny a single count of committing fraud by using a company credit card for personal gain between 1 January 2008 and 31 December last year.

Today the judge told the jury of five women and seven men that he had been shown a number of press reports concerning comments made by Cameron about the celebrity chef.

"They centre on the Prime Minister commenting about a prosecution witness, Ms Lawson, during an interview with a journalist.

"It is of regret when people in public office comment about a person who is involved in a trial which is in progress.

"It is inconceivable that some of your number may not have seen these comments.

"The defendants feel aggrieved as the comments, although they do not specifically deal with matters in the trial, are favourable to Ms Lawson.

"The fact that they may feel aggrieved is not without justification."

"You will realise that what public figures may feel about this case or a witness in this case can have no bearing on the issues that you have to decide."

The judge told the jurors that their decisions should be based fully on evidence and submission, all of which they would "hear in this room and nothing else".

Last week, Lawson admitted taking cocaine with ex-husband John Diamond when he found out he had terminal cancer, and on another occasion in July 2010 during her troubled marriage to Saatchi.

The 53-year-old also admitted smoking cannabis in the last year of her marriage to the art gallery owner but said the idea that she is a "drug addict or habitual user of cocaine is absolutely ridiculous".

Lawson spoke of suffering "intimate terrorism" at the hands of her multi-millionaire ex-husband, describing him as a "brilliant, but brutal man".

She accused him of "peddling" stories about her alleged drug habit, including that he was checking her nose for cocaine when he was photographed gripping her throat outside Scott's restaurant in Mayfair, central London, in June.

Both defendants deny all charges.

The trial continues.