The Guildhall organ pipework is arranged between four chambers above the proscenium arch. From right to left as facing the stage these are, Great/Choir, Swell, Solo, sub bass.

The ranks and items contained within each chamber are as follows:

 Sub Bass  Solo  Swell  Great/choir
 (Unenclosed)  (Enclosed)  (Enclosed)  (Enclosed)
 Sub bass pedal rank  Harmonic Trumpet  Rohr Flute  Diapason 1
 32ft Bourdon  Tuba  Flauto Traverso  Diapason 2
 Melotone horn  Tibia  Gamba  Diapason 3
   Harmonic Flute  Celeste  Diapason 4
   Vox  Hautboy  Principal
   Oboe  Fagottone  Stopped Diapason
   Strings (II)  Trumpet  Hohl Flute
   Cello  Geigen  Posaune 1
   Viole  French Horn  Posaune 2
   Celeste  Mixture II  Tromba
   Clarinet  Mixture III  Gemshorn
   Xylophone  Traps  Cor Anglais
   Glockenspiel    Lieblich Flute
       Vox Angelica
       Harmonics (III)
       Mixture II
       Mixture III
       32ft Diaphone
       32ft Posaune

As can be seen from the above (bearing in mind that this organ uses extension in many ranks) there are 41 units of pipes, if you count the sub bass as a unit and include the 32ft ranks as extensions. It can also be seen that there are five multi-rank mixtures and a strings rank, which consists of two strings (unison and celeste). This then brings the number of pipe ranks to 50 and if you count the Melotone as a rank this gives the usually quoted rank count of 51. Note that the diapason chorus is a clever combination of extended and non-extended ranks - e.g. the Principal 4ft is a separate rank, whereas Diapason 2 is extended. Also Posaune 2 appears at 16ft and 4ft on the Great and at 8ft on the Choir (i.e. it is extended down to 16ft and up to 4ft but its 8ft range is not available on the same manual). Posaune 1 however appears at 8ft on the Great, thus giving a full Posaune chorus to the Great with minimal missing notes.

From the above body of pipes, percussion, traps and Melotone and with very skilled use of a huge relay system, a classical console of more than 120 speaking stops and a very large theatre organ console draw their respective tone colours.

More details about the organ specfication can be found at NPOR: