Last year a hobbyist antiques dealer who had previously just sold 'odds and sods' took a punt on the teapot that was missing its lid, when he saw it for sale and bought it for £15.
He thought the piece that had a broken handle glued back together again, was common pearlware pottery and took it to expert Clare Durham of Woolley and Wallis Auctioneers in Salisbury, Wilts.
After handling it she suspected it might be non-English porcelain and further research established it was the work of Bartlam.
In 2002 four unmarked tea bowls and two saucers that sold at auction in the Midlands were later confirmed to be by Bartlam and the patterning on those matched that on the teapot.
It is thought the teapot and bowls formed part of the same tea service made by Bartlam at his factory in South Carolina and brought to Britain by him during a visit in 1769.
The excited middle-aged vendor was told the pot might sell at auction for anywhere, between £20,000 to £50,000.
But interest in it took off, especially from America, with bids going up by £5,000 and then £10,000 at a time at the auction