The organ here has an extensive history. It was first built by Walker in 1874 for Christ Church in Ealing, London and moved to St Mark's Church in North End, Portsmouth in 1909. It was rebuilt in 1925 by Rushworth and Dreaper of Liverpool and by Compton in 1955. In 1969 the organ was bought for £5000 and installed here at St Edmund's by Wessex Organ Builders. The organ is installed at the rear of the church with a separate division with it's own blower - the altar organ - installed at the front on the left. The console is on the right at the front and still retains the original Compton flat head drawknobs. The organ was rebuilt in 2002 by Robin J. S. Rust which included some tonal additions.

The specification reads:

Contra Bourdon 32'
Open Diapason 16'
Violone 16'
Bourdon 16'
Salicional 16'
Bourdon 16'
Octave 8'
Geigen 8'
Bass Flute 8'
Octave Flute 4'
Fifteenth 4'
Ophicleide 16'
Bass Clarinet 16'
Clarion 8'
Octave Clarion 4'

Violoncello 8'
Lieblich Gedackt 8'
Dulciana 8'
Lieblich Flute 4'
Salicet 4'
Nazard 2.2/3'
Piccolo 2'
Tierce 1.3/5'
Double Clarinet 16'
Clarinet 8'

Contra Geigen 16'
First Open Diapason 8'
Second Open Diapason 8'
Rohr Flute 8'
Octave 4'
Suabe Flute 4'
Gemshorn 4'
Twelfth 2.2/3'
Fifteenth 2'
Terz 1.3/5'
Mixture III
Tromba 8'

Open Diapason 8'
Orchestral Flute 8'
Viole 8'
Cor de Nuit 8'
Voix Célèstes 8'
Unda Maris 8'
Principal 4'
Open Fute 4'
Fifteenth 2'
Mixture III
Oboe 8'
Double Trumpet 16'
Trumpet 8'
Clarion 4'

BOMBARDE (played on choir)
Contra Tromba 16'
Tromba 8
Clarion 4'

ALTAR (played on choir)
Open Diapason 8'
Principal 4'
Fifteenth 2'

Choir to Pedal
Great to Pedal
Swell to Pedal
Swell to Choir
Choir to Great
Swell to Great
Choir/Bombarde/Altar Sub Octave
Choir/Bombarde/Altar Unison Off
Choir/Bombarde/Altar Octave
Swell Sub Octave
Swell Unison Off
Swell Octave

7 double touch thumb pistons to Choir/Altar/Bombarde and Pedal
7 double touch thumb pistons to Great
7 double touch thumb pistons to Swell
7 double touch toe pistons to Pedal and Great
7 toe pistons to Swell
3 reversible thumb pistons
Thumb piston to activate Choir to Pedal
Thumb piston to activate Great to Pedal
Thumb piston to activate Swell to Pedal
2 reversible toe pistons
1 reverse toe piston - Ophicleide 16'
1 general cancel thumb piston
1 balanced expression pedal with indicator - swell
1 balanced expression pedal with indicator - choir
Ventils to Choir Clarinet, Altar Organ and Tromba
Double touch canceller to each division