A collection of Byron’s letters in which he describes a stormy affair with a servant girl, attacks Christianity and dismisses his rival poet as William “Turdsworth” were sold yesterday for more than £250,000. The price is a world record for a series of letters or a manuscript by a British romantic poet, Sotheby’s said.

The letters, many of which are unpublished and have not been seen by scholars since the 19th century, reveal a highly personal side of the poet — described by his lover Lady Caroline Lamb as “mad, bad and dangerous to know”. The recipient was a clergyman, Francis Hodgson, who was no doubt scandalised by some of his friend’s exploits, although the two had a deep friendship that endured over many years.

Vitriol against other literary figures is a recurring theme. Byron is sometimes arch: “My modesty would naturally look at least bashfully at being termed the ‘first of living minstrels’ (by a brother of the art) if both our estimates of ‘living minstrels’ in general did not lessen the praise to a sober compliment.” At other times he is frankly crude, as in his jibe at “Southey and Turdsworth [and] other such renegado rascals”.

Byron writes happily from Portugal, noting that “the inhabitants have few vices except lice and sodomy”. From Turkey, he talks of meeting Ali Pasha and describes his swim across the Dardanelles, saying: “I do this that you may be impressed with proper respect for me the performer, for I plume myself on this atchievement”.

As Hodgson began to make attempts to convert Byron to religious orthodoxy, the poet offered sharp critiques of Christianity: “The Basis of your religion is injustice, the Son of God the pure, the immaculate, the innocent is sacrificed for the Guilty, this proves his heroism, but no more does away Man’s guilt, than a schoolboy’s volunteering to be flogged for another would exculpate the dunce from negligence, or preserve him from the Rod.”

Even more shocking, perhaps, was the description of an affair with a servant, Sarah Vaughan, which ended when Byron discovered her involvement with another man. The girl lost her job and reputation, and Byron captures her anger as she leaves “still threatening perdition, ‘thunder, horror guts & death’ ”. He adds: “I presume she will rave herself quiet.”

The collection of 71 handwritten pages was bought by an anonymous buyer for £277,250, far more than the original estimate of £150,00 to £180,000. “We are absolutely delighted with the price achieved for such an important collection of letters by Byron,” Gabriel Heaton, a specialist at Sotheby’s, said.

“There has been particular interest in what this unique collection reveals about Byron as a poet, as well as the more sensitive and thoughtful side to a man most frequently recognised as one of history’s most notorious Lotharios. The letters talk of love and poetry, of religion, travel and revolution, and their sale has offered a wonderful opportunity to reveal aspects of Lord Byron’s character that were either unknown or long forgotten.”

The letters were sold by descendants of the nineteenth-century prime minister Lord Rosebery. He bought the letters for £106 in 1885. The Times commented then that the letters were “written without the least reserve, as to a friend from whom he had no secrets, and evidently dashed off at red heat, the handwriting always bold and large”.

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