Nigella Lawson described as 'habitual criminal' in court Francesca and Elisabetta Grillo engaged in a 'greedy and fraudulent free-for-all' on the company credit card, court hears Pair were spending £50,000 a month on their cards during four-year scam They will claim 'intimate' atmosphere was created by Nigella Lawson's alleged drug use - and they were allowed to spend freely, court hears They shopped in Miu Miu, Chanel, Louis Vuitton and Prada, it is alleged Italian sisters worker for Nigella for more than a decade Charles Saatchi expected to give prosecution evidence tomorrow Jurors told the case is about fraud not 'matrimonial discord or drug taking' Panel told by judge they would be '12 unusual people' if they had not heard about allegations Nigella Lawson had taken drugs Nigella Lawson's two personal assistants claim that they were allowed to spend £685,000 on company credit cards is 'preposterous', a jury heard today. Italian sisters Francesca and Elisabetta Grillo lived the 'sort of life you may often see portrayed in glossy magazines' while working for the TV cook, a court heard. The pair allegedly splashed out on designer clothes from Chanel and Prada, and jetting off around the world on luxury holidays. Accused: Italian sisters Elisabetta Grillo (centre) and Francesca (right) spent £685,000 on their company credit cards, the jury was told They will claim that Miss Lawson took drugs and as a result they were given consent 'expressly or implicitly' to spend freely on the cards, the prosecution said. The four-year scam only finally unravelled when the millionaire art dealer's accountant spotted that Francesca, 41, and Elisabetta, 35, were spending £50,000 a month, it is claimed. Charles Saatchi, 70, is expected to give evidence for the prosecution tomorrow, while his former wife Nigella, 53, may take the witness stand as soon as Friday. Jane Carpenter, prosecuting at Isleworth Crown Court, said the pair claimed their 'exorbitant' spending was in exchange for silence about Nigella's alleged cocaine habit. She said: 'Despite the defendants' silence in interview, it is anticipated they will claim Mr Saatchi and Miss Lawson permitted them to use the credit cards to buy themselves presents and withdraw cash because of the long hours they worked. 'The defendant's case is that Miss Lawson's alleged drug use and the defendants' knowledge of it, materially affected Ms Lawson's attitude to the defendant's spending. An intimate atmosphere was created by this. Evidence': Charles Saatchi, 70, (pictured) is expected to give prosecution evidence against his two former employees tomorrow. His ex-wife Nigella is likely to enter the witness stand on Friday It is not their case there was a specific agreement for silence or acquiescence.Their case is that this expenditure was explicitly or implicitly consented to by Miss Lawson. But she said it was 'preposterous' to claim the couple approved the spending and that the two sisters were fraudsters. She said: 'The Crown says that although Mr Saatchi and Ms Lawson were generous employers, it is preposterous they would authorise such a level of personal expenditure by two personal assistants. This is a case about fraud. You may well be aware of matters in the press concerning Mr Saatchi and Miss Lawson, specifically the incident at the Mayfair restaurant in June and allegations of drug taking made by Mr Saatchi about Miss Lawson more recently. 'These details are secondary, they have little relevance as to why Francesca and Elisabetta committed these offences, we say it's fraud motivated by greed, and that is what this trial is about, not other issues of matrimonial discord or drug taking. If they had been allowed such privilege, it would have meant Francesca was paid more than the highest paid employees of any of his businesses. The duo had worked for Nigella for more than a decade and were treated as trusted members of the family who lived with them rent free and went on family holidays. But over four years between 2008 and 2012 they fraudulently used the company credit card to splash out on luxury outfits, holidays and gifts to themselves. Drug claims: Nigella Lawson's former workers will make allegations about her alleged drug use, the jury was told today They shopped at Miu Miu, Chanel, Louis Vuitton and Prada and stayed in top hotels abroad. Ms Carpenter said: 'This trial, the prosecution say, relates to the high life lived by Francesca and Elisabetta Grillo. The sort of life you may see portrayed in glossy magazines. But they did so not by their own endeavours, but in a greedy fraud free for all abusing the trust if their employees in a four year spending spree. The court heard that the pair were allowed to use credit cards to spend money on household expenses and things for the couple's three children. She said: 'For some people, however, the temptation of having a card which they can use with impunity to buy high value goods is too great. 'It must be a dishonest employee's dream to have a company credit card that is always accepted. These two defendants were employed by a wealthy family and invested with a high degree of trust. But they decided to abuse their credit cards and went on a four year spending spree. They travelled the world, staying in top hotels and spent exorbitant sums of money on designer clothes and accessories. By the time their fraud came to light they had incurred expenditure which was in excess of £685,000. Francesca, who was paid £28,000 a year, the younger of the sisters, spent the lion's share racking up £580,000 on the card. Her older sister Elisabetta, who earned £25,000, spent £105,000 on the card registered to Mr Saatchi's Conarco Partnership firm. Divorce: Nigella Lawson and her ex-husband Charles Saatchi, 70, are both set to give prosecution evidence against their two former PAs And they racked up a fortune on taxi travel on the company's account, it is claimed, with Elisabetta getting a taxi to go to a polo match in Berkshire. Concerns were sparked in June last year when Mr Saatchi's finance director Rahul Gajjar noticed their expenditure had rocketed from £10,000 to £20,000 a month, to £50,000 a month. The pair confessed to using the cards for personal expenditure, but initially Mr Saatchi hoped to resolve the matter 'amicably'. In a meeting with Mr Saatchi on July 20 last year at the Saatchi Gallery in London's Kings Road, the sisters agreed to stay on as employees and pay back the cash gradually. But in a later meeting with Mr Saatchi's finance director the defendants balked at the pay back plan. Claims: TV cook Nigella Lawson has faced court claims that she took drugs. However, jurors were told this afternoon that the case before them is about fraud Ms Carpenter said: 'The defendants became aggravated and angry and refused to sign the letters. He tried to placate them but the meeting broke down without agreement. Mr Saatchi met with Francesca the next day in a bid to reach an agreement. Ms Carpenter said: 'Her attitude was it was humiliating to live in the house on less pay and would rather go to jail. It left Mr Saatchi feeling there was no choice but to initiate proceedings. The police were called in and the sisters were arrested on August 2 last year. The sisters' lawyers earlier failed in an attempt to get the case thrown out. Accused: Francesca Grillo (left) and her sister Elisabetta (right) leave Isleworth Crown Court this afternoon after the jury heard they spent £685,000 on credit cards Giving the jurors a series of directions, Judge Robin Johnson said: 'You would be 12 unusual people if you had not in the past couple of days heard about this case. It has been widely publicised in the press, radio and television. 'There's nothing to stop you reading reports and there's nothing to stop you continuing to read reports. Please bear in mind that is not something which should affect you, unless of course it perfectly coincides with your reflection of the evidence. The Grillo sisters both face one charge each of fraudulently using Mr Saatchi's Conarco company credit card. Francesca wore a white shirt and black dress as she sat next to her sister Elisabetta, who wore all black, flanked by an Italian interpreter and custody officer in the dock. The sisters both deny one count each of fraud between January 2008 and December 2012.