It was the insects found roaming in Jeremy Bentham's underpants that did it. Almost 200 years after University College London's "auto-icon" was created from the philosopher's body, the appearance of the bugs suggested that it was time for the conservators to get involved.

Bentham's recent adventures started in 2001, when the Ruhrland Museum in Essen, Germany, asked to borrow the body for an exhibition.

A survey of the auto-icon was ordered prior to any shipping and this revealed the infestation. The undergarments wrapped around the skeletal frame were full of "woolly bear" insects and the waxwork head crawled with carpet beetles.

And so the work began. The auto-icon's fabrics were removed, cleaned and treated in UCL's Textile Conservation Centre and the bugs freeze-dried into oblivion; while in 2003, the Institute of Archaeology began a condition assessment of the physical remains.

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James Hales, UCL's collections conservator, took the opportunity to gain a better understanding of how the auto-icon was made.

At about this time, US film-makers the Engels brothers requested a loan of Bentham's preserved head for a documentary on mummies. Technically the auto-icon is a defleshed skeleton, not a mummy, but the movie moguls' cash was useful, funding the endoscopy and high-resolution X-ray work that enabled the team to probe inside the wired skeleton and head.

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They found the bones are attached to a two-piece iron central armature, which is bolted on to Bentham's favourite chair (see picture, right). The ensemble is all held together with pins and twisted loops of copper wire.

The bones are yellowing and slightly greasy, suggesting they were not fully degreased when stripped of flesh. But bone condition throughout the skeleton is good with only one break, on the right ankle, probably done - and repaired - during the original preparation process.

Some work was needed to repair the waxwork head, where the insects had done their worst and hair had been rubbed away by the straw hat.

Now Bentham is in a better condition than he has been for years, and Hales hopes the auto-icon will be treated with more respect in future.

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"If it were in a museum, it would be an important piece," he says.