The Scott collection of more than 100 clocks, watches and scientific instruments contains 47 items made by or with direct links to the 'father of English clock making' Thomas Tompion and his successor, George Graham.
Advised by clock expert Richard Garnier, former head of Christie's clock department and later Jonathan Carter among others, the late Channel Island businessman and philanthopist Tom Scott, who died in 2012, built his unrivalled collection of these early timepieces over 30 years. Tompion highlights - many of them trophy purchases from London sales or fairs - include:
• The Lonsdale Tompion, a rare blued steel and gilt brass miniature timepiece table clock dating to c.1683, one of a harlequin pair of miniature metal case table clocks, the other being in the Fitzwilliam Museum, Cambridge.
• The Royal Exchange Tompion (c.1688-90), one of only three known examples by Tompion, one of which is in the Royal Collection.
• The Medici Tompion, c.1696, an ebony and gilt-brass mounted grande sonnerie table clock, which William III presented as a gift to Cosimo de Medici. It was last seen at the Grosvenor House fair in 2007 when priced at £2.25m.
• The Hanover Tompion, c.1704-08, a tortoiseshell and gilt-brass mounted grande sonnerie bracket clock and one of two ordered by George of Denmark, Queen Anne's husband.
Jonathan Carter of Carter Marsh will unveil the collection at the Masterpiece fair in London before putting it on sale across two exhibitions - in July and November - at the Winchester gallery. Prices for individual pieces range from £2000 to £4.5m.
"It's a once-in-a-lifetime opportunity not just for us but also for collectors to acquire clocks of this rarity and quality," he said. "Just to have three grande sonnerie clocks by Tompion in one place at one time is extraordinary in itself."
Other highlights of the collection include what could possibly be the missing third longcase regulator installed in the Octagon room at Greenwich Observatory and a surveying compass signed in manuscript by the great John 'Longitude' Harrison, dated 1718, and made for his own use. It is the only known instrument by him.