Cherie: Nobody ever used to pick on Denis

Cherie Blair today complained bitterly that she was being singled out for criticism over her money-making jaunts.

The Prime Minister's wife told an audience in the US that she was a victim of sexism and that Margaret Thatcher's husband had never been treated as poorly.

"Denis Thatcher also had a number of outside interests. Nobody found anything wrong with that," she said in a speech at the Kennedy Center in Washington DC.

Mrs Blair is rumoured to have been paid as much as £30,000 for the 90-minute talk on the eve of her husband's visit to President George Bush in Washington.

The "coincidence" of Mr and Mrs Blair being in the US capital has prompted accusations that she is cashing in on her role as the Prime Minister's wife.

Mrs Blair tried to laugh off the matter, saying: "It has crossed my mind that of all the 365 days in the year that Tony could have come, this was not my favourite." She said her appearance in Washington had been booked before her husband's White House visit.

The Conservatives pointed out that Mrs Blair would be accompanying her husband to an official engagement with the President and the First Lady tonight.

Mrs Blair said she accepted that she would never receive 100 per cent approval ratings. "I just think you can't please all the people all the time... what you must do is be true to yourself."

She blamed her predicament on the fact that previous prime minister's wives had been of a generation when fewer women worked. "It's a terrible sort of tightrope one is walking all the time - professional life and the wife of the Prime Minister," she said. "Because each of the women were different, they had to do it their way. There are no rules for what to do."

Mrs Blair received a warm reception at the 2,500-seat Opera Hall, especially when she praised the relat ionship between Britain and the US.

The one-off engagement follows a lecture tour in Australia

earlier this year which earned her a reported £100,000. The row over her earnings has caused disquiet on the Labour benches, with MPs fearing she is damaging her husband. "There is an issue," said one backbencher.

The Conservatives today stepped up their calls for Mrs Blair to follow the example of US First Lady Laura Bush by donating the proceeds from her engagements to charity.

Christopher Grayling, the shadow leader on the House, said: "For the past week No 10 has been saying that her visit is an entirely private one. Now it seems that they have been misleading us - she is staying at an official residence at the taxpayer's expense, and will be joining her husband on official business. This is completely unacceptable."