The 1549 Book of Common Prayer (BCP) is the original version of the Book of Common Prayer, variations of which are still in use as the official liturgical book of the Church of England and other Anglican churches. Written during the English Reformation, the prayer book was largely the work of Thomas Cranmer, who borrowed from a large number of other sources. Evidence of Cranmer's Protestant theology can be seen throughout the book; however, the services maintain the traditional forms and sacramental language inherited from medieval Catholic liturgies. Criticised by Protestants for being too traditional, it was replaced by the significantly revised 1552 Book of Common Prayer.