Old bones, stained teeth, one trunk and the Missing Link Piltdown fraud turns up in

After 43 years of detective work, the search for the perpetrator of the biggest scientific hoax of the century is finally over - and the motive has been revealed as one man's wish for a weekly wage instead of piecework payment.

"Piltdown Man", a faked fossil discovered in 1912, ruined the reputation of Arthur Smith Woodward, keeper of paleontology at the Natural History Museum. He went to his death-bed insisting that the skull discovered in a Sussex quarry was that of the earliest Englishman, and that the carved elephant bone found with it (shaped suspiciously like a cricket bat) was genuine.

But in 1953, five years after Woodward died, the fossils were shown to be fakes: the skull, instead of being the "missing link" between ape and man, was composed of an orang-utan jaw and a man's head. The other fossils were also found to be fakes, made of stained and carved old bones.

However, the identity of the hoaxer remained a mystery. Over the years, it was blamed variously on Charles Dawson, a lawyer who first found the remains, on Sir Arthur Conan Doyle, creator of Sherlock Holmes, and on Teilhard de Chardin, the noted priest and palaeontologist.

But the discovery by the Natural History Museum of an old canvas trunk in its attic seems to have answered the question. Inside were human teeth, which had been stained like those of the "fossils". The trunk's owner was the late Martin A.C. Hinton, the museum's curator of zoology at the time of the fraud.

"I'm 100 per cent certain that it was him," said Brian Gardiner, professor of paleontology at King's College, London, yesterday. "The contents of the trunk clinch it."

Professor Gardiner first had a hunch that it was Hinton in 1953, when he was working at the museum as a student as the fraud was exposed. He will give a lecture on his conclusion tomorrow night to the Linnean Society. "Hinton was known as a practical joker. Dawson was the fall guy for his practical jokes, just a gullible solicitor. Hinton's motive is shown by some letters," he said yesterday.

"In 1910, Hinton was just a summer student working there in his holidays, and he wrote to Woodward asking to work at the museum cataloguing rodent remains." He was offered pounds 130 - after the work was complete. Hinton, then 27, asked for a weekly payment. Woodward is thought to have been unmoved - which piqued Hinton, a prodigy who at 16 had had a paper published on how fossils become stained by river deposits.

The contents of the trunkshow that Hinton produced the fakes by careful staining; the teeth were his test runs. The key clues for the Piltdown detectives are the presence of traces of chromium metal in the teeth, the trunk - and the Piltdown bones. The chromium is the missing link which finally fingers Hinton.

The only question that remains is why Hinton did not own up once Woodward had swallowed the bait. "I think it was all taken so seriously and attracted so much attention that he couldn't," said Henry Gee of the science journal Nature, which today publishes a full account of the search. "The trouble now is that all the suspects are dead and buried. You would have to be Inspector Morse to answer that one."