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THE row engulfing the Tory party over expenses deepened this weekend as it emerged that Sir Robert Atkins, the MEP and former minister, used his parliamentary expenses to fly to his son’s wedding in America.

Atkins, 62, who served in the Thatcher and Major governments, attended the ceremony at Montclair, New Jersey, in November 2006. He said that it “coincided” with an official invitation, making it possible for the taxpayer to pick up travel and hotel bills.

The disclosure that public funds helped to pay for Atkins’s trip will add to the pressure on David Cameron.

Caroline Spelman, the party chairman tasked with ensuring that MPs’ expenses are beyond reproach, was this weekend defending her decision to use expenses to pay her nanny for secretarial work. She is to refer the matter to the parliamentary standards commissioner. “I thought I was entirely within the rules – and that is still my belief,” she said.

The expenses row is a setback for Cameron after his party’s surge in the opinion polls. It was triggered after The Sunday Times disclosed last weekend how Giles Chichester, the Tory leader in the European parliament, had channelled £445,000 of expenses via a family firm.

Atkins insisted that he had fully complied with parliamentary rules for the wedding trip. He said the event coincided with an invitation from the Republican National Committee and in a statement this weekend emphasised that his expenses were approved by the parliamentary authorities.

“The allowance contributed to the cost of my flight, hotel and travel to the various locations where I was either campaigning or discussing current political issues with Republican party members [in New York, New Jersey and Connecticut],” he said.

Atkins is also among the many MEPs who put family members on the payroll. His wife, Dulcie, is employed as a secretary and his son, James, worked for him in Brussels until 2004.

Cameron is expected to demand more transparency on expenses.

Hugh Thomas, the party’s head of compliance, will travel to Brussels this week to scrutinise MEPs’ claims. One of the practices to be reviewed will be the use of companies for paying staff and providing parliamentary services.

Den Dover was removed as chief whip last week as it was revealed that he had paid up to £750,000 to a firm run by his wife and daughter.

The accounts of the Dover family company, MP Holdings, reveal that it spent £32,000 on repairs, thought to be on the family’s Hertfordshire home. A further £56,411 went on motoring costs and £75,397 on postage and stationery.

The spotlight turned back to Westminster on Friday as it was revealed that Spelman had paid her nanny out of parliamentary allowances. Conservative Central Office said Tina Haynes – Spelman’s nanny for 5½ years – was paid as a constituency secretary from 1997-8. Spelman faces questions about the amount of secretarial work involved.

The donation was registered with the Electoral Commission as a gift to the Tory party. But a spokesman for his firm said he had made donations to Duncan’s private office.

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