A missal provides all the prayers, hymns, and readings necessary for the celebration of Mass over the course of the year. This deluxe 15th-century missal made for use on the altar was given to the church of St Lawrence in London by William Melreth, alderman, textile merchant of Broad Street and eventually member of Parliament, probably just before he served as Sheriff of London. Near the end of the missal, an image of the book's donor, William Melreth, alderman of London, in prayer before the Trinity serves as a heading for an inscription detailing his gift of the splendid missal to St Leonard's in 1425. Melreth's heraldry appears on the shields at the feet of the Trinity, and the words "Blessed be the Trinity" are inscribed in gold in the background and below picture. The latin inscription states that he had it made for the altar. In the picture, God the Father sits enthroned behind the Crucifixion, the white dove of the Holy Spirit barely visible above the head of Christ.