PA tells court Nigella Lawson unhappy in marriage and blocked from working abroad by Charles Saatchi

Isleworth Crown Court, west London, heard the siblings bought designer clothes, shoes and luxury holidays.

But Francesca told the jury in court eight that she was given a bank card to withdraw her own salary and buy "anything I wanted".

She described her relationship with Mr Saatchi and Ms Lawson, who divorced earlier this year, as being as close as family. Ms Lawson would often confide in her about her job, her husband and her desire to break America.

Ms Lawson appeared on an American television programme this year but kept putting off an earlier offer before that show began because her then-husband did not approve, the jury was told.

"Charles didn't like the idea of her being away for too long," said Francesca.

Asked by defence counsel Karina Arden if Ms Lawson was happy, Francesca replied: "I think in general, no. In her relationship, no.

"She's a very social woman. She likes people. She is a people person and Charles is quite opposite.

"Many, many occasions she had to turn down things, going out, because Charles didn't approve."

Francesca said she was handed a bank card upon first being employed by art dealer Mr Saatchi more than a decade ago, with the simple instruction to withdraw her £300 a week wages and to buy anything she, Mr Saatchi, Ms Lawson or their children needed.

She told the court the card was used to furnish her new accommodation in the annex of Mr Saatchi's house, as well as pay for essentials such as groceries.

Giving evidence in her defence, Francesca said she played a key role in the lives of Mr Saatchi, Ms Lawson and the children - including housekeeping, shopping, taking the children to school, cooking meals and even cleaning up after builders to prevent Mr Saatchi from getting angry over the mess they left.

Francesca told the court she was responsible for giving money to the children - often up to £80 each, five days a week.

The defendant said she withdrew the cash from a company account to pay for the children's travel costs and for food if they ate out in the evening - and said Ms Lawson was fully aware of the situation.

Francesca admitted she liked designer labels, and there were times when she bought herself expensive items - but said all were authorised by Ms Lawson.

The court heard logs on the credit card included one in excess of £5,000 at the high-end fashion retailer Miu Miu. On each occasion, the designer goods, which included a pink fur coat and a Christian Dior handbag, were gifts from her boss, who she described as "extremely generous".

She stressed that Ms Lawson always knew about the purchases.

Francesca said: "We would be talking and I would say I really like this item or these things, and she would be like 'You can go and get them'.

"Any items that I bought, Nigella knew about."

Questioned by Ms Arden about Ms Lawson's evidence earlier in the trial that she would not have authorised such large payments, Francesca replied: "I'm afraid Nigella said many things that are not quite true."

The court heard the company credit card had been extended to a £100,000 limit - up from £50,000 - but Francesca said she did not ask for this to happen, just that the payments were met while she was on holiday with the children and was conscious of creeping close to the previous credit limit.

Francesca told the jury she still loved Mr Saatchi, Ms Lawson and the children - but said she was disappointed with the case being brought to court.

Referring to the trial, Francesca told the jury: "When something like this is happening, you don't stop loving them."

The Grillos, 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 January 1, 2008 and December 31 last year.

The trial was adjourned until tomorrow morning, when Francesca will continue giving evidence.