The dark olive green glass-handled shaft and globe, 8 1/4in (20cm) high, carries an estimate of £12,000-15,000 at BBR on July 6.

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The rare English transitional shaft and globe with a handle still intact, c.1660-1670, was a chance find for bottle hunters Bill Leitch and Steven Bolt in April. It was skilfully excavated with a stick from under tree roots at a site in Cornwall.

The finders, believing it was an 18th century 'onion', listed it on eBay only to be met by a flurry of bids and offers of up to £2500 well in advance of the sale ending. They decided to halt the sale and enter it at BBR's showpiece auction timed to coincide with the Summer National bottle festival.

Since its discovery, many serious collectors have enthused over the significance of the find, its attractive overall surface patination and great condition. Many rate it as the finest ever dug English bottle.

The estimate is £12,000-15,000, with the current 'black' glass record - the £18,000 established by a shaft and globe at Bonhams in December last year - under threat.

Enthusiasts unable to make the show and catch the sale of lot 154 can listen in live on www.the-saleroom.com (free to register, then click on the BBR catalogue).

By Roland Arkell