
The substantial sanctuary has a modest canopy over the high altar rather than the intended baldacchino. The two seven-branched candlesticks were given by the Marquess of Bute. On the right there may be seen two of the 17th-century Apostles' statues from Siena.
The principal facade has a lower storey that is brought forward from the nave to create a narthex and that also embraces the single-storey aisles. Gribble originally intended flanking towers, but they were never built. The entrance features four pairs of Corinthian columns and pilasters with a balustraded parapet above. The pedimented nave is surmounted by a statue of the Virgin Mary, and has the arms of St Philip Neri in the tympanum. The transepts reach to the same height as the nave, forming a Latin Cross, which is domed at the crossing. The dome was supervised by George Sherrin, but it is thought that his assistant, Edwin Rickards, was its main designer. The dome is taller than Gribble had intended, but as a result it is easier to see from Brompton Road. A memorial to Cardinal Newman by Farmer & Brindley stands to the west of the entrance, incorporating a statue by L. J. Chavalliaud.
The organ gallery, which houses the instrument completed in 1954 to Ralph Downes's design.
The Lady altar was made for the Dominican church at Brescia in Italy in 1693, but the central statue of the Virgin Mary came from the first London Oratory near the Strand.
The broad nave is three bays long, and each bay is flanked by side chapels set at right angles to it. Pairs of giant Corinthian pilasters in Plymouth marble articulate the nave; pairs of much smaller Corinthian columns support the arches into the chapels. Between the pilasters there are statues of the Apostles, carved by Giuseppe Mazzuoli between 1679 and 1695, which once stood in Siena Cathedral. On the left-hand side, near the crossing, there stands Commendatore Formilli's pulpit of 1930, with a substantial carved tester and a staircase on each side. The crossing is flanked by the Lady chapel on the right and the chapel of St Philip on the left. The Lady altar, a towering Classical composition, is also an old Italian work, for it was made in 1693 for the chapel of the Rosary in the Dominican church at Brescia. For that reason, it features statues of four Dominican saints, but the central statue of Our Lady of Victories came from the first London Oratory near the Strand. Gribble himself designed St Philip's altar, which was the gift of the 15th Duke of Norfolk. A wax effigy of the saint lies beneath the altar. For the high altar, Gribble had intended a baldacchino such as the one we see at Westminster Cathedral, but this plan was not carried out, and instead there is a modest canopy. A painting of a scene from St Philip's life stands behind the altar, and two more fill the side arches of the sanctuary. In the south-east corner of the church there is a large additional chapel of St Wilfrid, whose high altar is an 18th-century work from the church of St Remy at Rochefort, Belgium. Father Faber's grave lies in front of the altar, with a Latin inscription on the stone; St Wilfrid was his chosen patron. In the same chapel, the altar of the English Martyrs has above it a triptych by Rex Whistler, 1938, which depicts Thomas More and John Fisher, who were then newly canonized. The shrine of St Cecilia, also in this chapel, has an effigy that copies the one by Stefano Maderno in her church in Rome.
A view from the south-west corner of the church towards the Lady chapel, across the various side-chapels. A First World War memorial featuring a white marble pieta stands under the arch on the left.
Rex Whistler's altarpiece of the English Martyrs in St Wilfrid's chapel, 1938, showing St Thomas More (left), St John Fisher (right) and executions at Tyburn (centre). More and Fisher had been canonized in 1935.
The organ was designed by Ralph Downes and built by J. W. Walker & Sons in 1954. The church has a distinguished musical tradition, which is one of the features that ensures the Oratory a significant place in the life of the Catholic Church in London.