As the midnight oil burned and student Ibrahim al-Marashi hurried to complete his post-graduate treatise on Iraq's intelligence network, little did he suspect where it might end up.

Earlier this week the essay, albeit in a slightly modified form, quietly reappeared as part of a dossier of evidence against Saddam Hussein drawn up by Downing Street.

Has the government blotted its copybook?

Only when the similarities came to light a few days later did the government put its hand up. A Downing Street spokesman said the government had never claimed exclusive authorship.

Yet when the boot is on the other foot, Tony Blair's government has not been shy to bandy about charges of plagiarism.

Five years ago, Downing Street delighted in pointing out how William Hague, then leader of the opposition, had seemingly cannibalised a speech made by Tony Blair some years before.

In 1998, Mr Hague told a conference: "We can say to the elderly person who is afraid to go out at night for fear of being attacked - we are on your side."

If you steal from one author, it's plagiarism - if you steal from two, it's research American screenwriter Wilson Mizner

Click here to compare the dossier with student's report

Which wasn't so dissimilar from Mr Blair's stated intentions in 1994: "To the pensioners who fear to go out of their homes - we are on your side."

The resulting fuss quickly died down. But sometimes the ugly clash of plagiarism and politics can have a devastating impact for those involved, as US senator Joe Biden will attest.

The congressman is one of those being tipped for the Democrat ticket to run against George Bush in the 2004 presidential election. But the last time Mr Biden showed such ambition, in 1987, he was publicly humiliated after it was alleged he had pilfered parts of a speech from the then British opposition leader, Neil Kinnock.

A source of inspiration in the United States

A Biden speech had gone: "I started thinking as I was coming over here, why is it that Joe Biden is the first in his family ever to go to a university? Why is it that my wife who is sitting out there in the audience is the first in her family to ever go to college?"

All of which sounds eerily similar to Neil Kinnock's very public musing: "Why am I the first Kinnock in a thousand generations to be able to get to university? Why is Glenys the first woman in her family in a thousand generations to be able to get to university?"

However, in the arts, hardly a week seems to go by without allegations of plagiarism from some quarter or other.

Plagiarism or parody?

One of the most notable recent cases is that of 2002 Booker prize winner Yann Martel. No sooner had the Canadian author scooped the prize for his book Life of Pi than allegations started to fly that he had purloined the idea from a Brazilian author. Martel freely admitted he had been inspired by Moacyr Scliar's Max and the Cats.

Dolly the Sheep: Ultimate victim of plagiarism?

Other authors who have had their originality questioned include fellow Booker winner Graham Swift, and JK Rowling.

In the US, Pulitzer winning historian Doris Kearns Goodwin has been labelled a "serial offender" after she admitted "accidentally" using unattributed passages from three different works in her book The Fitzgeralds and the Kennedys.

Musicians also like to surreptitiously tip their hat.

A couple of years ago, Robbie Williams revealed a hitherto hidden liking for American roots music when it emerged his track Jesus in a Camper Van, which appeared on the best-selling album I've Been Expecting You, copied substantially from songs by Woody Guthrie and Loudon Wainwright III.

Robbie Williams 'plagiarises' that Last of the Summer Wine look

The singer was ordered to remove the track from all future copies of the album.

Old time rockers the Rolling Stones saw red when they dutifully pointed out that Bitter Sweet Symphony, by British band The Verve, had sampled an old Stones track.

Yet in folk and blues circles, "borrowing" is worn as a badge of pride - for years musicians have unashamedly fashioned new lyrics over familiar old tunes.

In fact, it's only in the last two or three hundred years that plagiarism has become such a dirty word, most particularly in Western society.

Will the real Saddam Hussein please stand up

"It is related to the idea of the artist as genius, someone using unique gifts to reach as closely as possible to the ideal form which exists," says The Bloomsbury Guide to Human Thought.

"Until the Renaissance, this kind of originality was not required: artists, and thinkers of all kinds, were part of a continuum of creativity and invention, and their work was legitimised by its relationship to the whole field."

But if Downing Street really wants to be consoled, perhaps, it should bear in mind that when it comes to covert duplication, Saddam Hussein is perhaps its greatest exponent - the Iraqi leader is said to have a handful of look-alikes who stand in for him at various occasions.