[2] The structure is incomplete, lacking two bays on its liturgical west side (which prevented the construction of a planned façade – the west end remains unfinished, in brick apart from entrance in stone) and (like Westminster Abbey) a crossing tower (including a 150 ft spire – the tower base that was built has mostly blind arcading).

Its cruciform plan is made up of a nave with full triforium and clerestory, side aisles, sanctuary and Lady Chapel.

The five-bay nave (only 13 feet lower than that of Westminster Abbey) has a gabled east facade with three large lancet windows below five smaller ones – on the inside, it has a timber hammer beam roof with angels and central bosses of snowflake design, as well as a double-arcaded triforium.

[2] Annette Peach, in her entry for Raphael Brandon in the Dictionary of National Biography, writes: "The Catholic Apostolic Church in Gordon Square, London, was built between 1850 and 1854 and, though reproducing features recorded by the Brandon brothers in their scholarly works, this extremely large church was criticized by a contemporary for its lack of originality of design.

[4] Recent scholars, however, have drawn attention to the combination of 13th- and 15th-century Gothic precedents in its design, which offer a tangible record of the Brandon brothers' study of ecclesiastical architecture.

During this period, a Thanksgiving Eucharist was celebrated on 27 November 1988 for the 25th anniversary of this role, with the Right Reverend Michael Marshall preaching and, on 6 December 1983, the memorial service for Nikolaus Pevsner was held here.

[9] The last Chaplaincy Sunday service was held on 28 June 1992, but a weekday Eucharist continued to be celebrated in the English Chapel.

The last chaplaincy service was conducted on Ash Wednesday (16 February) 1994 by the Reverend Alan Walker of the University of Westminster; The Diocese surrendered its lease on the church to the Trustees on 30 June.