Well red at Oxford

Inside an old trunk destined for a car boot sale, a thrilling cache of letters has emerged to shed light on the student days of the revolutionary firebrand and poet, P B Shelley. Suzi Feay is transported by a brilliant philosophical prank

The letters are strung together on ancient blue cord and there are traces of a blob of sealing wax. Nearly 200 years ago, the recipient filed them and forgot about them. But the paper is not so brown and decayed as you might expect, and the content is immortally fresh. Susannah Morris, the manuscripts expert at Christie's who has been investigating the letters' provenance and history, has discreetly withdrawn and left me alone to commune with them. Am I going to read them, or am I, like the William Blake-crazed serial killer of Thomas Harris's novel Red Dragon, going to take the precious relics, roll them up and eat them in order to assimilate the author's vital essence?

I pick up the letter addressed from "49 Lincoln's Inn Fields, Dec 15 / 1810". "The plan of an universal language has my warmest & sincerest support," is all I can make out. Heavy stuff. But the real thrill comes at the end: " ... be so good as to direct to me at Field Place, Horsham, Sussex. I am, Sir, yr most obt. servant Percy Shelley."

In January this year, Morris's colleague Crispin Jackson paid a house call to "an unassuming semi in a nice street" to help assess the contents. "You could tell it had been a bloke's house; it was cluttered and very dusty - we went through masses of gloves." There were books - "literature and junk-shop stuff"- dating from the 1600s, in home-made bookcases lined in newspaper from the early 1960s, piles of 78s, musical instruments, and theatrical and sporting memorabilia.

Upstairs, Jackson found several cardboard boxes of manuscripts, and a small wooden chest about the size of a tuckbox - "It looked early 19th century to me. Being nosy, and aware that manuscripts are very sought after, I had a look." There were letters from H G Wells and Arnold Bennett, one Dickens letter and old photograph albums (including one featuring female impersonators), but the real treasure lay at the bottom, "right on the wood". The four letters in two different hands were addressed to a Mr Wedgwood. One of the senders appeared to be a "Rev.d Percy B Shelley", and from what Jackson could decipher, it was a passionate philosophical tirade against religion.

"The 'Reverend' bit was puzzling, but I'd read Paul Foot's Red Shelley, so I knew all about the radical side of his life," says Jackson. "Foot wrote it to show that Shelley wasn't a doe-eyed, dreamy sailing enthusiast, but a tough political activist. Shelley's prose can be difficult to read, but I think he wrote to be read aloud. The letters are declamations."

Jackson hurried to tell the new owner of the find: "She told me she'd been thinking of sending the boxes to a car boot sale".

When the letters, two by Shelley and two by his almost equally interesting friend, Thomas Jefferson Hogg, go on sale at Christie's on 8 June, anyone with a spare £20,000 to £30,000 has the chance to acquire a fascinating and moving piece of literary history. The "Reverend" Shelley hoax began as an undergraduate jape; but Shelley's incessant need to bait Christians culminated two months later in the pamphlet "The Necessity of Atheism", which got both Shelley and Hogg expelled from Oxford. This was to turn the son of a minor Sussex baronet into a rebel and an outcast, and precipitate his career as one of the most brilliant poets in the language.

Shelley went up to Oxford in the autumn of 1810. An eccentric and isolated figure who kept his own routine, rarely meshing with the life of his college, he found a soulmate in the more pragmatic Hogg. They became inseparable, talking passionately late into the night, and Hogg later gave an unforgettable glimpse of the range and sparkle of the young poet's conversation. "Again after supper the theme of chemistry and its wonders was taken up; the service it was destined to render to the race of man; the supply of unstinted stores of untainted food; the watering of arid African wastes by streams and lakes won from the elements by chemistry; the production of artificial heat in arctic climes, and for our poor during the cruel English winters; the mighty energies of the galvanic battery; the art of aerial navigation in balloons."

Oxford, a dusty intellectual backwater in those days, bored the two students stiff. This was the age of the Lunar Men, of exciting advances in science and thought. Shelley was as passionate about science as about poetry, and was to share his scientific enthusiasms with his future wife, Mary; Frankenstein is the most famous result. Hazlitt, reviewing the verse years later, would deliver the weary put-down: "I could wish [Shelley] would put a stop to the incessant, alarming whirl of his Voltaic battery."

After hours of this alarming intellectual whirl, Hogg remembered: "I lighted him downstairs with the stump of a candle... and I soon heard him running through the quadrangle in the still night. That sound became afterwards so familiar to my ear, that I still seem to hear Shelley's hasty steps."

This, then, is the backdrop to the newly discovered letters. It's the archetypal student experience: you've had one term at college, made an exciting new friend, and now it's the Christmas hols and you have to go back to your boring parents. The two friends scribbled furiously to each other; and Hogg eagerly took up Shelley's hobby of spamming unsuspecting correspondents with atheist propaganda. A favourite trick was to pose as a cleric who is losing his faith. The recipient, aghast at this prospect, invariably responded with fervent arguments supporting Christianity. The bold young freethinkers then hooked their confused prey with more and more tightly argued polemic. Here's where the letters to Wedgwood come in. But which Wedgwood?

Susannah Morris's researches point to one man: Ralph Wedgwood (1766-1837), cousin of the great Josiah. Ralph, no less than Shelley, was a man of his age. He was the inventor of carbon paper, and in one letter Shelley asks for some more "semi-carbonic paper" to try out. Both students are excited by his new invention, the "othiothograph", designed to "introduce an entirely new basic system of notation for letters, numbers and musical intervals". Morris's researches in the British library show that this device was patented on 18 July 1810, patent no 3362.

But the real meat of the correspondence lies its religious controversy. "Christ never existed," protests Shelley, "the fall of man, the whole fabric indeed of superstition which it supports can no longer obtain the credit of philosophers." Hogg weighs in with his own arguments, marshalling Greek and Hebrew with impressive authority to reject the notion of language as formed by a deity. Shelley himself quotes Spinoza and Locke, and it is awe-inspiring to see a level of intellect and learning in two first-years that would not disgrace a PhD student today.

Most exciting of all, the letters fit into the existing Shelley correspondence in the archives. The watermarks and sizes match two Shelley letters in the Bodleian. The Field Place letter is written on paper that matches a known letter to Hogg dated a week later, which suggests a stock of paper actually kept in the house (Shelley's childhood home). A letter to Hogg dated 14 January, 1811, and printed in the 1915 edition of the complete letters, begins: "My dear friend, Your letter and that of W[edgwood] came today... I inclosed five sheets of paper full this morning and sent them to the coach with yours. I sate up all night to finish them..."

"When I read that," says Jackson, "I went back to one of my letters and counted the sheets - there were five. That was a tremendously moving moment, holding them."

So it's a little bit of radical history that is up for grabs in June. "I think Shelley was probably a bit like George Galloway," Jackson concludes mischievously. "He liked a fight. Anything that would annoy the establishment, that's what he loved to do."

The Valuable Printed Books & Manuscripts sale, which includes first editions of 'Northanger Abbey' and 'Persuasion', Milton's 'Areopagitica' and George Orwell's 'Nineteen Eighty-Four', takes place on 8 June at Christie's, 8 King St, London SW1 (020-7930 9060). All sales are on public view three days before the auction. Viewing is free and accessible to all