St George's Cathedral originally contained an instrument believed to have been built by Bishop and Son in 1890. This was replaced in 1935 by an instrument which had originally been built by Lewis in 1905 for John Courage and installed at his home in Wonersh, Surrey. He had left the organ to the Cathedral in his will. On the night of 16th April 1941 during the blitz, the Cathedral was hit by an incendiary bomb, starting a fire which destroyed the wooden roof and much else. The Cathedral was rebuilt after the war and consecrated on 4th July 1958. The new organ was built by the John Compton Organ Company Ltd.

The organ is built in true Compton format using the extension principal with 19 ranks of pipes installed in 2 enclosed chambers located east of the south transept. However, the patent 32ft polyphonic bass is unenclosed as is a fantastic Tuba! The drawstop console is located behind a screen at the very front of the cathedral below the east window. Each swell box has 2 sets of shutters directing the sound into either the chancel and nave but there are also drawstops to allow these to be controlled separately. It is said that when originally installed, tonal finishing had to be done during the night due to the noise of trains running nearby! The organ received an overhaul in 2000 and apart from a few tonal changes, remains very much original and is a superb example of a large instrument built by Compton in the post war years.

The specification reads:

PEDAL
Sub Bass 32'
Sub Bass 16'
Contra Bass 16'
Open Metal 16'
Contra Viola 16'
Bourdon 16'
Principal 8'
Octave 8'
Stopped Octave 8'
Geigen 4'
Octave Flute 4'
Octavin 2'
Mixture IV
Harmonics 32'
Bombarde 16'
Posaune 16'
Hautboy 16'
Posaune 8'
Clarion 4'

CHOIR
Double Dulciana 16'
Open Diapason 8'
Gemshorn 8'
Stopped Diapason 8'
Dulciana 8'
Vox Angelica 8'
Principal 4'
Stopped Flute 4'
Dulcet 4'
Nazard 2.2/3'
Dulcet Fifteenth 2'
Flautino 2'
Tierce 1.3/5'
Sifflote 1'
Acuta II
Clarinet 8'
Contra Posaune 16'
Posaune 8'
Tuba 8'
Tuba Clarion 4'
Tremulant

GREAT
Double Diapason 16'
Bourdon 16'
First Diapason 8'
Second Diapason 8'
Third Diapason 8'
Hohl Flute 8'
Stopped Diapason 8'
Octave 4'
Principal 4'
Open Flute 4'
Twelfth 2.2/3'
Fifteenth 2'
Fourniture IV
Cymbale III
Contra Posaune 16'
Posaune 8'
Clarion 4'

SWELL
Contra Viola 16'
Geigen Diapason 8'
Viola da Gamba 8'
Voix Celeste 8'
Harmonic Flute 8'
Geigen Octave 4'
Viola 4'
Harmonic Flute 4'
Nazard 2.2/3'
Fifteenth 2'
Piccolo 2'
Cymbale III
Contra Hautboy 16'
Trumpet 8'
Hautboy 8'
Clarion 4'
Tremulant

COUPLERS
Choir to Pedal
Great to Pedal
Swell to Pedal
Swell Octave to Pedal
Swell to Choir
Choir to Great
Swell to Great

SHUTTER DRAWSTOPS
Chancel Shutters On
Nave Shutters On

ACCESSORIES
8 double touch thumb pistons to choir and pedal
8 double touch thumb pistons to great and pedal duplicated by toe pistons
8 double touch thumb pistons to swell and pedal duplicated by toe pistons
8 general thumb pistons
6 reversible thumb pistons
1 reversible toe piston - great to pedal
Pedal combinations to great pistons
2 balanced expression pedals with indicators
10 ventil switches
1 general cancel thumb piston
1 setter thumb piston
Voltmeter