A pastel profile of George Washington by James Sharples – £25,000 at The Cotswold Auction Company.

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This is because many of his works depicting the celebrities of the period were duplicates. You might call him the Andy Warhol of his day.

The amateur artist, who led an itinerant life after arriving in New York in 1796, became increasingly prolific as he refined his rapid pastel technique.

He was able to complete his works within two hours and, with the aid of a pantograph (an instrument for duplicating a shape), was able to create inexpensive copies of original portraits that he made of popular figures such as George Washington, James Madison, Thomas Jefferson, Hester Thrale and John Adams.

Working with his wife Ellen, also a talented artist, numerous copies of his profile of Washington are known for which he charged $15. Today at least 26 are recorded (including some solely by Ellen), although distinguishing between the hands of husband and wife is a difficult task.

Since 2005, five copies have emerged at auction – four of them making under £20,000 before one spectacularly fetched $260,000 (£189,570) at Christie’s New York in January. That example had a long recorded provenance and came to auction from the collection of John William Middendorf II, a former US diplomat and secretary of the navy.

Family collection

More recently on this side of the Atlantic another appeared at Cotswold Auction Company (22% buyer’s premium) in Cirencester on October 19, although it did not quite reach these heights.

The 9 x 7in (23cm x 18cm) pastel was catalogued as by Sharples himself (rather than Ellen or another family member) and was believed to have once been owned by 19th century British collector Jeffery Whitehead.

It came to auction from a family collection in the Cotswolds that had also yielded a rare book from 1773 by the African-American poet Phyllis Wheatley that sold for £16,500 in June (see Books & Works on Paper, ATG no 2504).

Here the estimate was set at £30,000-50,000, a level that proved to be a little punchy as it was knocked down at £25,000 to a London phone buyer.

The sum was, nevertheless, the second highest recorded for a Sharples profile of Washington and the highest ever for one his works sold in the UK.