In the words of Ernest Shearman:- “The Church is designed on the Basilican model with wide nave affording the whole congregation an uninterrupted view of the Sanctuary and Pulpit; the Altar being the centre of the Apse.”

The plain severity of the exterior does not prepare one for the array of shrines and decorations that beautify the stark plainness of the interior as one enters by the south entrance. This church is a simple brick building with six bays of capital-less arcades, arch braced roof, passage aisles, an additional chapel on the south side and an apsidal chancel with a narrow ambulatory.

The interior appears lofty and spacious and because of the large clerestory windows (mainly with plain glass) is very light. The two eastern-most nave bays have deep clerestory recesses that form false transepts. On either side of the nave there are narrow passage aisles that are set aside for devotional purposes. The chancel arch is formed from two gothic arches, one super-imposed over the other. The chancel is narrower than the nave and terminates in a polygonal apse pierced by five tall lancet windows. The apse roof is supported by a half cartwheel like construction. The chancel is encircled by an ambulatory passage that is pierced by seven gothic shaped openings. The chancel is raised three steps above the nave with a further step to divide the chancel from the sanctuary area. The High Altar is then raised a further three steps in accordance with Tractarian worship for which St. Silas was designed. Therefore the High Altar is seven steps above the level of the nave so that it becomes the focus of attention. To heighten the focus on the altar, Shearman designed the great baldacchino, more correctly known as a ciborium, to rise above the altar.

Remove the shrines, the statues, the altars, the banners and all the other items of devotion and one is left with a very austere building. Shearman designed this church to be beautified by its people. Over the years this has happened, mainly due to the initial devotion and diligence of its first priest, Father G. Napier Whittingham. He set the seal on the future tradition of this church.

From the east end of the church one can see the gallery with its organ and choir area. To the left of the gallery is the Altar of St. Joseph.

Adjoining the south passage aisle is the Chapel of St. Francis of Assisi now used as the sacristy. Next to it, in the south-west corner of the church, is the confessional area which was formerly used for the shrine of the Pieta.

The gallery at the rear of the church extends between the nave arcades. The case and pipe work of the now disused organ, built in 1914 by Bishop & Sons, is mounted on the west wall. In 1994 an electronic 3 manual, 43 stop organ by Copeman Hart was installed. This instrument is voiced on continental French models. On the north side of the organ loft there is access by narrow staircase to the now redundant chapel of St. George, which is at second floor level.

There are four stained glass windows in the body of the church which were donated by a member of Fr. Whittingham’s congregation who wished to remain anonymous. They are of the Madonna and Child situated in the south of the gallery; of Hope situated above the confessional area; of St. Cecilia situated in the south-west of the gallery; and of St. Michael situated in St. George’s Chapel.

It will be noted that there are a number of long Latin inscriptions in and around the church. These are to be seen in the section - Latin Inscriptions.

Statues of many saints are to be found in this church. Most of these can be seen in the Statues and Shrines section.