Organs regarded as worthy of conservation or restoration
The significance of an old organ increases with its age, rarity, and the extent to which it remains in its original state. Organs of any size from the seventeenth, eighteenth or first half of the nineteenth centuries in any state of preservation are now so rare and of such historic importance that their preservation, and, if necessary, faithful restoration, should be assumed as a matter of course. Organs of the period 1850-1920 survive in somewhat greater numbers, but again their preservation and restoration should normally be the rule. Organs from 1920 onwards may not be historic as such, but nevertheless major unaltered examples of the work of good builders should be preserved in their original state.
Organs that have been so radically altered that they no longer represent the style of the original builder may be of lesser interest, though some such instruments may still contain extremely important historical material. Any organ case, pipework or mechanism more than a hundred years old should be considered for preservation.
Organs, like other musical instruments, are works of art. The most significant examples rank alongside famous violins and paintings by great masters though, as they are fixtures and not often marketable, their monetary value may well not reflect this. Even the most humble examples represent great care and skill on the part of their makers, and the temptation to alter them to conform to tastes in playing that the maker did not envisage should be avoided. Nor should it be imagined that the non-sounding parts of the organ are just mechanism, and can be changed at will; each part has a vital role in affecting the way the instrument can be played, and therefore the way it will sound.
Some historic organs now have their status confirmed by the award of a Historic Organ Certificate, although the listing programme is currently incomplete.