By the autumn of 1937, an impression of the shape of the new House could be gathered from the steel girders and cross-pieces then in place. In December it was announced that the contract for the superstructure had been given to Messrs Dove Brothers of Islington.
A year later the walls had reached second-floor level. Special coloured flints were used to decorate the lower part of the building, in which the flint-masons inserted rebuses - pictorial puns commemorating those responsible for the construction. To the right of the entrance porch a wheel, a thistle and a loaf of bread symbolise Charles Wheeler (sculptor) and Alex Scott and Sir Herbert Baker (architects). To the left, the builders and the Secretary are depicted by a dove and a partridge. The flints came mostly from Sir Herbert Baker's native Kent and also from Cambridgeshire. Winchester College gave some, and in these is set the heraldic shield of that See. Above the entrance doors are the arms of the Provinces of York and Canterbury, with two bondstones commemorating King Ulphis of Northumbria and King Aethelbert, who gave lands to the first Churches in York and Canterbury. The Anglo-Danish and Anglo-Saxon lettering was supplied by J.R.R. Tolkien.
The wealth of architectural detail executed by, among others, Charles Wheeler and Laurence Turner (modeller and carver), is described and explained by Sir Herbert Baker in The Church House. Its Art and Symbolism. Published in 1940, this invaluable book is still largely valid except for the description of the painting above the altar in the Chapel, designed by Sir Herbert Baker to express the poem, 'In No Strange Land' (also known as 'The Kingdom of God'), found after his death among the papers of the poet Francis Thompson (1859-1907).
When the building was first opened, the space above the altar was filled with a cartoon (the work of a student) from the pre-war designs by Tom Monnington, RA, who had been chosen by Sir Herbert to paint the final work. This had to be deferred when the artist was occupied on war service. In 1943 Sir Herbert, who had donated £300 towards the cost of the picture, approached Monnington to complete the painting but the artist explained that the war had changed his outlook on art and he was out of sympathy with the work. Subsequently the cartoon was removed and 'The Adoration of the Shepherds,' by Pierino del Vaga, an early sixteenth-century Italian artist, was purchased by the Corporation in 1962.