Built by J.W.Walker & Sons and completed in 1954, the Oratory’s organ is one of the most important built in London in the post-World War II era.   Possessing 45 stops on 3 manuals and pedals, it was designed by Ralph Downes, Organist of the Oratory 1936-77 who was the most influential British organ designer of that period, responsible for the organs in the Royal Festival Hall, St Albans Abbey and Gloucester Cathedral amongst others.  

It was completely restored and overhauled in 2004-5, scrupulously preserving its original tonal design.  Its specification is quoted in full in The Cambridge Companion to the Organ (1998) as the model of modern English organ design, and the late Stephen Bicknell described it in Choir & Organ, 1997 as: ‘…an instrument of peerless tonal quality, perhaps the best of all the organs designed by the late Ralph Downes’.

The Oratory also possesses two other fine modern instruments, a 2-manual, 16-stop instrument in the Little Oratory by Flentrop of Holland, built in 1975 and restored by the original builders in 2005 and a 3-stop chamber organ by Peter Collins of 1979, restored in 1998, in the sanctuary.