A single prayer in the services before Hymns of the Spirit beginning "Almighty God grant that the words" comes from a book identified in the index as the Theistic Prayer Book. What is this and where did it come from?
It comes from the Theistic Church in London, that lasts from 1870 or 1871 until shortly after the 1912 death of its founder and minister, Charles Vorsey, who was driven out of the Church of England. (He's the father of the famous architech of the same name, if your mind goes to the Arts and Crafts.) At the church, the book was known as The Revised Prayer Book, and ran through three (1871, 1875, 1892) editions.
In both Hymns of the Spirit (p. 146) and The Revised Prayer Book, the prayer appears in a section for additional prayers (in the third edition); it appears, slightly re-arranged as prayer for the "close of worship" in Hymns of the Spirit.
Cross-posted at Hymns of the Spirit.