Dame Maggie Smith has declared the show must go on after being diagnosed with breast cancer.

According to reports, the double Oscar-winning actress has had a tumour removed and has also completed a course of chemotherapy.

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Dame Maggie in Tea With Mussolini, for which she won a Bafta

Friends described her as "typically brave and understated". One added: "The last thing she wants to do is to make a fuss about it."

Dame Maggie, 73, insisted on completing her sixth appearance as Harry Potter schoolmistress Minerva McGonagall in Harry Potter And The Half-Blood Prince while having radiation therapy.

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Dame Maggie Smith, who is best known for her portrayal of Professor McGonagall in the Harry Potter films (pictured, with Emma Thompson), is said to be battling breast cancer

She is due to begin work on Julian Fellowes's film From Time To Time, an adaptation of Lucy M Boston's book The Children Of Green Knowe. Filming has been delayed, however, by several weeks to allow for her recovery.

Dame Maggie, pictured here at a recent awards show, reportedly doesn't want a fuss made about the illness

A spokesman for Mr Fellowes said he expected to begin filming "within the next few weeks" but no specific date has been set.

Dame Maggie is regarded as one of the country's pre-eminent actresses, with a prolific stage and screen career spanning 50 years.

She won her first Oscar in 1969 for her portrayal of a Scottish schoolmistress in The Prime Of Miss Jean Brodie.

Her second, for best supporting actress, came in 1978 for California Suite.

She was nominated for a third Academy Award for her snobbish turn as the Countess of Trentham in the 2001 film Gosford Park.

She has also won five Baftas. She won a Theatregoers' Choice award last month after her return to the West End stage in The Lady From Dubuque.

Among her many other notable roles was Charlotte Bartlett in the Merchant-Ivory film A Room With A View, co-starring Helena Bonham Carter, for which she won a Golden Globe award.

Dame Maggie married fellow actor Robert Stephens in 1967 and they have two sons, who are both actors.

The younger, Toby Stephens, 38, played a villain in the James Bond film Die Another Day. Sir Robert and Dame Maggie divorced in 1974 and she married playwright Beverley Cross in 1975.

At the time of his death ten years ago she was appearing in A Delicate Balance at the Theatre Royal, Haymarket, but continued in the role until the end of the run.

She once said in the past: "It's true I don't tolerate fools, but then they don't tolerate me, so I am spiky. Maybe that's why I'm quite good at playing spiky elderly ladies."