THE Duke of Wellington

defeated Napoleon to become a national hero - but met his own Waterloo in the form of Lady Georgina Fane, his most persistent female admirer.

The 19th century stalker made life a misery for the Iron Duke - bombarding him to the end with ''daily vituperative letters'' and threatening to publish his love notes.

Details of her ladyship's lifelong obsession with the handsome soldier who went on to become prime minister are revealed in an unpublished letter which has surfaced during a clear-out at Fulbeck Hall,

Lincolnshire, home of the Fane family for nearly 400 years.

In the letter, a desperate Wellington - by now aged 82 - begs Lady Georgina's mother, the Countess Dowager of

Westmorland, to persuade her spinster daughter to stop ''molesting'' him with unwelcome correspondence.

An exasperated Wellington, writing from Walmer Castle in October 1851, the year before his death, protests at Lady Georgina's refusal to return his private letters to her - despite her promises to do so.

The duke also says that she has ''shewn these letters to others with a view to calumniate, to injure, to vex and torment'' him.

Wellington, whose military achievements had earned him a knighthood in 1805, was

something of a ladies' man, notwithstanding his marriage in 1806 to Kitty Pakenham, who bore him two sons.

But the dalliance with Lady Georgina caused nothing but grief to one of the most powerful, wealthy and charismatic

figures in the land. After being close, she later tried to sue the duke for an alleged breach of promise to marry her and threatened publication of his love

letters.

The four-page letter, expected to fetch up to (pounds) 4000 at the (pounds) 1m sale of the contents of Fulbeck Hall at Sotheby's in London on October 8 and 9, begins: ''My dear Madam I have long had it in contemplation to appeal to your Ladyship and to request your Ladyship's interference with your daughter Lady Georgina Fane to prevail upon her Ladyship to cease to molest me with daily vituperative

letters.''

He writes that he was told this by someone ''to put me on my guard'' and later heard that Georgina had tried to show the letters to several others.

He describes Georgina's actions as ''extraordinary'' and says they ''betrayed such lack of good faith'' that it was impossible for him to continue any acquaintance.

Kerry Taylor of Sotheby's, who has catalogued the Fulbeck treasures, said: ''Wellington was demonstrably angry when he wrote the letter.

''This is reflected in his handwriting. Our history expert, Peter Beal, has seen may pieces of Wellington's writing and none of it is anything like this.

''Georgina pursued him - and her claim of breach of promise - until his death. This unpublished letter reveals the depth of her obsession with the duke.

Georgina first met Wellington at a ball soon after his 1815 victory at Waterloo - when she was just 14. During her 20s and 30s their relationship turned to romance - one that was to haunt him for the rest of his days.

The duke was no stranger to threats over his love life. When an unscrupulous publisher said he could hold back the kiss-and-tell memoirs of another woman in his life, Harriette Wilson, the duke famously replied: ''Publish and be damned.''

Fulbeck Hall was wartime headquarters of the First

Airborne Division and it is now up for sale, in October there will be an auction of the contents of the house.