Do contact Gardiner Houlgate if you haven't received a copy to the Christopher Hogwood Instruments catalogue yet.
Here is Item 10, a spinet by Handcock, 1732. A lovely instrument, nearly 20 years later than the Keene and Brackley spinet which I have for sale. The guide price (between £8,000 and £12,000 ) plus buyer's  premium of 20% plus Vat, is in line with what I would expect. Some of the other prices (£2,000 to £3,000 for a square Piano by Pohlmann, 1773 restored by Lucy Coad in 2014) seem low. None seem very high - so come and grab a bargain.