Former Holy Trinity Church

Holy Trinity Church, in Marylebone, Westminster, London, is a former Anglican church, built in 1828 by Sir John Soane. In 1818 Parliament passed an act setting aside one million pounds to celebrate the defeat of Napoleon. This is one of the so-called "Waterloo churches" that were built with the money. It has an external pulpit facing onto Marylebone Road, and an entrance with four large Ionic columns. There is a lantern steeple, similar to St Pancras New Church, which is also on Euston Road to the east.

By the 1930s, it had fallen into disuse and in 1936 was used by the newly founded Penguin Books company to store books. A children's slide was used to deliver books from the street into the large crypt. In 1937 Penguin moved out to Harmondsworth, and the Society for Promoting Christian Knowledge, an Anglican missionary organisation, moved in.