The church's website tells us about the history of the building:
"A place of worship has existed on the site of the present church since 1787 when a Chapel of Ease was built by Lord Portman to commemorate the Battle of Quebec (1775). The orginal chapel was reputedly converted from the riding school of the Portman Barracks. By the early twentieth century the chapel had become delapidated and in 1911 it was pulled down.
The inspiration behind the new building was the Revd Bernard Day Douglas Shaw. Walter Tapper (1861-1935) was chosen as the architect. Tapper was an authority on church architecture. He was a Royal Academician, a Fellow of the Society of Antiquaries and President of the Royal Institute of Architects. In 1928 he became Surveyor to the Fabric of Westminster Abbey where he is buried.
Artist's impressions prior to construction were painted in the office of Charles Gascoyne (1887 -1917). The view of the exterior is in the Royal Academy. The view of the interior is owned by the church. The entry in the RA Exhibition catalogue for 1912 says
“Walter Tapper was elected a full Royal Academician on 12 February 1935, was knighted on 23 July and died on 21 September. But, within a month of his election, he had submitted his Diploma Work, this drawing for the Church of the Annunciation, a building squeezed into the back streets near Marble Arch. Tapper was a quiet and reflective architect. He was chief assistant and then manager in the office of George Bodley RA and Thomas Garner before setting up full time in his own practice at the relatively ripe age of forty. Preferring to keep a close check on his designs, he never employed more than four draughtsmen at a time. Tapper is said to have gained honours for his ‘positive goodness’ and ‘honesty’, qualities which the architect Charles Reilly said commanded ‘affection and respect’ (Reilly, p. 157). Deeply religious and of a high church persuasion, Sir Walter Tapper was principally an ecclesiastical designer, the architect of many churches. He held the position of Architect to the Fabric of Westminster Abbey, where he now lies buried in the cloisters. But he could also turn his hand to more prosaic matters, as he had a good sideline in creating showrooms and gas fires for the Gas Light and Coke Company. His son and later architectural partner Michael John Tapper recalled that the Church of the Annunciation, a fine lofty building, with something of the scale of a cathedral or a major medieval church, was his father’s favourite work. The street elevations are windowless at ground level, but high windows and vaulting throughout give the interior spaciousness. The church’s rich furnishings are in keeping with the Anglo-Catholic tradition. In 1912, the year construction began, Tapper showed this drawing and another of the interior at the Royal Academy’s Summer Exhibition. Both were by Charles Gascoyne, the popular perspective artist who died as a prisoner of war in Germany in 1917. This moody and introspective scene is played out beneath the great east window and flying buttresses on the north side of the church. The winter day is rainy and blustery. A woman fights the wind with her umbrella. Another, wrapped up against the weather, skirts a puddle in the road. But her umbrella is folded, the rain has passed, and the church is bathed in the emerging sun, catching on its spire – created by a touch of gouache – hinting at the heavenly light of hope.”
The Annunciation is in the style known as Edwardian Gothic. Pevsner notes that to enter the Annunciation is to have stumbled upon 'a fragment of a major medieval church'. Tapper was a pupil of G.F. Bodley (1827-1907) who was a leading light in the resurgence of interest in English and North European late medieval design.
The church has many fine furnishings. The high altar reredos was designed by Tapper and executed by J.C. Bewsey (1880-1940). Bewsey also designed the stained glass.
The organ case is by Tapper and may be based on J. L. Pearson's 1817-1987) organ cases in Westminster Abbey. The organ was built by Frederick Rothwell (1853 - 1944).
The Rood supporting Christ on the Cross flanked by the Blessed Virgin Mary and St John is in the shape of the rainbow, a symbol of the covenant between God and creation.
In the north aisle the Somerset Memorial is dedicated to Norman Somerset who was a close friend of the Prince of Wales. He was killed aged 20 at the First Battle of Ypres (1914).
The floor of the sanctuary contains a fine brass memorial to the Revd Bernard D. D. Shaw, the only brass known to have been designed by Tapper. It was engraved by hand.
The Stations of the Cross are by Alois de Beule of Ghent (1861-1935). They are plaster casts of originals in wood.
The single bell was cast in 1913 by John Warner & Sons, Spitalfields.
The Annunciation also contains some furnishings brought from elsewhere. The lampidarium spanning the arch between the sanctuary and the Lady Chapel originally hung above the high altar of St Chad's Cathedral in Birmingham and was designed by A. W. N. Pugin (1812-1852)."
The church is Grade II* listed with the entry at the English Heritage website telling us:
"Church. 1912-13, by Sir Walter Tapper. Red brick with stone dressings, slate roof. Late Gothic Revival with strong vertical emphasis; bold simplicity in balance of blind wall place to windows and restrained use of carved ornament. Hall nave and chancel of 8 bays with north aisle. The south Bryanston Street front has 2 storey stone faced porch at west end with figure sculpture in niches above shafted jamb portal. The porch projects level with the bold gabled buttresses dividing the 8 bays which are blind up to the tall clerestory lit by 4-light reticulated tracery windows; parapet with weathered coping. The east gable end to Old Quebec Street is flanked by similar buttresses with 2 buttresses under large east window of individual, crisply carved, reticulated tracery pattern; above the aisle parapet a flying buttress springs from right hand gabled bell tower with vestry entrance at its foot. Railings to street run between buttress piers with gable caps. Steep pitched roof with slender, copper-clad fleche with gablets to centre of ridge. Vaulted interior has lofty, slender shafted arcade and triforium on north side; gilt altar by Bewsey."