It was designed by E. G. Paley in the Gothic Revival style and is a grade II* listed building.

In 1901 a baptistry was added by Austin and Paley, and the east end was reordered in 1995 by Francis Roberts.

[4][10] The golden jubilee of the church was celebrated in 1909, and a number of alterations were made under the direction of Giles Gilbert Scott.

[12] When the centenary was celebrated in 1959, the pipe organ was refurbished, and the painted Stations of the Cross were replaced by a set of carvings.

The steeple stands at the northeast corner, and the octagonal baptistry is attached to the north transept.

On the west side of the bottom stage of the tower is a gabled north porch, above which is a canopied niche containing a statue of St Peter, and a three-light window.

[16] Inside the cathedral are six-bay north and south arcades, and a west gallery carried on marble piers.

To the west of the chapel, behind the high altar, is a large reredos designed by Scott; this consists of a triptych containing paintings and carvings.

The baptistry contains a central marble font, an altar with a reredos, and stained glass windows by Shrigley and Hunt.

[18] The original organ in St Peter's was moved from the mission church in Dalton Square.

[23] In the Buildings of England series, Hartwell and Pevsner express the opinion that the church is the "chef d'oeuvre" of Paley's works.

[3] The building is in active use as a Roman Catholic cathedral, which arranges Masses and other regular services,[26][27] and organises concerts and other events.