We have from the beginning aimed at following museum principles of restoration. These principles can be summarized as:
research the organ’s history as far as possible, in the archives and in the organ itself
retain as much of the original material as possible
repair only as required and not wholesale
retain the patina of age and not falsify the nature of the historical evidence
leave a complete photographic and descriptive record of the restoration
There are always compromises and dilemmas. Almost all organs are working instruments. They have to function well and meet the demands of today. Only very rarely, e.g. at Calke Abbey (anonymous chamber organ ca1750), and St Luke’s Smithfield Virginia (anon consort organ 1630) have we conserved the organ without the alterations necessary to make the organs work well.
Some of the inevitable compromises can be met by engaging with another conservation principle; that a musical instrument should be restored to the last point at which it was a viable and complete musical instrument, meeting the demands of a particular moment in musical history. Many English 18th century organs have been comprehensively rebuilt in the 19th century, in a way that preserves some of the earlier work but transforms the essential character of the organ. Sometimes the later work has itself suffered alteration. Sometimes the later work has been badly or superficially done. But the idea should always be to return the organ to some point in its history, and not be tempted to update it or make it more versatile for modern purposes.
We have not always been able to resist the temptation, particularly in providing pedal stops for organs which are otherwise restored to their 18th century condition, e.g. at St Helen Bishopsgate (Thomas Griffin 1743) or St Botolph Aldgate (Renatus Harris 1704). A good argument for making a historic organ more versatile is that it is then more widely used. Unless it is in a museum collection (and even then!) an organ is more likely to be valued and its condition monitored if it is regularly used.
Sometimes restoration is a frustrating business. The organ at St Swithun Worcester was built by the brothers Gray in 1795 as a single manual organ. Only shortly after in 1822 it was made quieter, stops were replaced, a third mixture rank was removed, and most disappointingly the Trumpet was replaced with a Dulciana. The temptation to replace the Trumpet particularly was resisted, but with a heavy heart, especially as the organ now has an 1845 short compass swell organ, and the Trumpet could suffer from the restricted access for the tuner.
But sometimes it can be very rewarding. At St Mary and St Nicholas Worcester (Thomas Parker 1766) there was a providential fire which destroyed the Victorian parts of the organs but spared the Georgian parts. The reconstruction of Parker’s organ could be based on the altered but preserved elements of his organ, the keys and wind chest, and about 75% of the pipework.
One possible solution to the dilemmas is to make a copy of the original organ when the alterations have to be preserved in the restoration. It is usually an impractical solution because the customer is satisfied with the restoration for which the funds have been raised. And the relationship of an organ with its church and its original position within it is a valuable a part of its testimony. With small organs it is more feasible, but we have only once restored an organ and made a copy of it. We restored a ca1700 Italian chamber organ for Sheila Lawrence, as we found it, and made a copy as a hire organ in the early music world (though with a transposing keyboard and the treble Voce Umana which is the sound chiefly associated with the classical Italian organ).
The survival of the wind chest(s) is usually the key to a restoration. It provides and fixes the specification of the organ, so it is difficult to move far from the original stoplist and key compass. If stops have been exchanged or altered, it is usually in association with the provision of other wind chests, a Swell organ or Pedals. If the original wind chest survives it can authorize the return of the organ to its original stoplist and key compass, as it did at St Helen Bishopsgate. No modern organist would choose to have a compass from GG to d³, but the use of the old chest leaves the possibility for organists to explore the music of the period with their low notes.
It is amazing how often the date to which the organ is restored is the date of the wind chest. It makes it all the more galling that the work of the two emblematic builders of classical English organs, Bernard Smith in the 17th century and John Snetzler in the 18th century, is not represented by a single surviving wind chest, not in their church work at any rate. So the church organs of these builders can only be re-created by reconstructing their work in new organs, or by assembling surviving parts. The 1777 Snetzler organ at Rotherham Minster has the case, the keys and console and parts of 19 of the original 20 stops surviving. It would need a new mechanism, but the project would be distinctly possible.
The work of restoring an organ can be an agonizing business. Trying to preserve the character of the original and retain original material wherever possible means that each pipe and each bit of mechanism passing across the workbench required a mini-decision; whether the original material will survive for the next century, or whether it needs to be replaced. At point does the character of the organ cease to be as obvious to future generations as it still is for us. Leather usually has to be replaced, just because of its natural deterioration; it cannot be conserved, repaired and reinforced if it is to do it essential jobs as a seal or a hinge. Occasionally the corrosion in a country church organ is such that the screws or pins have to be replaced rather than repaired; then they go into a museum box under the organ.
Most agonizing is the tonal work, because it is the most important and the most fugitive. Not historic organ will sound as it did originally, but it is usually possible to pick out pipes which have been altered least by time or human hand, and use them as models for the others. All the actions of time, settlement, wear and tear, and developing taste tend to make an organ quieter, and to favour the bass over the treble, and the unison stops over the upperwork. Nonetheless, it is often safer to regulate the volume of the pipes to the mean, though one could choose to regulate them up to the loudest pipes. In either case, a note should be left in the restoration report.