Standing 12 feet tall, John Byfield’s house organ dominates the dining room at Finchcocks, a Georgian manor house in the heart of the Weald, Kent. A stunning case design by “Mr Adam” - in fact John Adam, brother of the more famous Robert - featuring limewood carvings framing the gilt front pipes, provides an arresting sight for visitors to the museum; this is generally the first room they visit.

What makes this instrument exceptional is its superb condition. The Byfield was made in 1766, but many other instruments from the period have, at some point, been altered. This was sometimes to keep up with the prevailing views on pitch, which rose steadily (and meant cutting down the pipes of an instrument), or modifications to the specifications (adding or changing rows of pipes, extending the keyboard compass) according to current fashions.

In this instrument the pipes are virtually untouched and still at their original pitch - nearly a semitone below the present standard and almost the same pitch as a tuning fork belonging to Handel, offering some clue as to a general pitch level in London in the 1750s.

Other original details are preserved, too. There are slips of paper attached to the organ’s console in the maker’s handwriting which describe suggested pipe combinations. Byfield even offers the following advice: “In drawing of the stops, take care that they be put as far out or in as they will go, or else the Organ will appear out of tune.”

Another feature kept intact is out of sight: underneath the sound-board (on which the pipes are seated) are pasted sheets of paper to seal the board.

These are old legal documents, presumably from Byfield’s company archives.

The organ was built in London for Castle Grant, Banffshire, and cost its first owner, Sir James Grant, pound;250. A letter from a member of Sir Grant’s staff mentioned that the last pound;50 was paid to Byfield, as he was “very hungry”.

Finchcocks acquired it in 1975 and, after being rebuilt in the oak-panelled dining room, it has been played regularly ever since, being featured on recordings and in weekly demonstrations to members of the public.

Since Finchcocks is now licensed for civil marriage ceremonies, the organ often provides musical accompaniment to the proceedings. A very fitting usage for this majestic and important instrument.

Steven Devine is assistant curator at Finchcocks Living Museum of Music, Goudhurst, Kent TN17 1HH. The house, with its collection of nearly 100 historical keyboard instruments is open to the public on Sundays between 2-6pm, Easter to October, and by appointment at other times. Tel: 01580 211702.