The building is in an early Italian Romanesque style, with a basilica plan. St Margaret's pioneered a break away from the Gothic tradition in the district with outstanding success. It is now protected as a Grade II listed building.

St Margaret's is built of concrete, which is roughcast rendered with decorative brick bands and dressing around the windows and doors.

The plain, sober exterior contrasts strongly with the luminous, mainly white painted interior. The church is generously lit on all sides by round headed leaded light windows on north and south aisles, a high range of clerestory windows, three high small rounded windows in the apse at the east end and a large Venetian window in the south aisle chapel. Despite alterations to the height of the organ, light still comes in from the arched windows at the west end.

The interior plan is simple and harmonious, with an arcade of Tuscan columns dividing the Nave and Aisles, and an open kingpost roof.

In 1986 the Chancel was re-ordered and redecorated in red, gold and green to emphasise it as the focal point of the church.

In addition to his involvement in the building's architecture, Nicholson was also responsible for designing many of the original internal fittings for St Margaret's including:

• the high altar, the chapel altars and the altar rails,
• the original stalls
• the pulpit (the original design included elaborately carved gilded panels to match the high altar but were never completed).

All other major furnishings were submitted to him for approval. Father Hilditch had great confidence in the judgement of Nicholson in such matters and was anxious that the harmony of his architectural creation should not be marred by the indiscriminate introduction of unworthy additions. Other features of interest include:

• the stone font in the back right hand corner of the church. The base is made of black marble and the wooden cover depicts the waters of baptism, the gate of salvation and the Holy Spirit in the form of a dove.
• The small stained glass window in the north aisle depicting St Michael fighting the dragon, which commemorates a parishioner killed in the Second World War.
• The stained glass window of the Lady Chapel, depicting the adoration of the Magi.
• The statues of our Lady with the Christ Child in the Lady Chapel and Our Lady of Walsingham, by Anton Wagner, in the alcove to the right of the south door.