The first notable figure of this architectural revolution was Thomas Rickman, who was based in Birmingham for 21 of the 23 years he practiced as an architect. Although he worked in a wide variety of architectural styles Rickman's understanding of Gothic was far more thorough and learned than that of most other architects of his time, and his Quaker background gave him a systematic and objective view of Gothic styles free from the complications of the Church of England's search for liturgical meaning. His earliest Birmingham church St George-in-the-Fields of 1819 (demolished) was a remarkably correct Gothic structure for its date, and moved away from the economical but historically inauthentic use of cast iron detailing of his earlier churches in Liverpool. It was followed by a series of other notable works in the Birmingham area, including St Barnabas' Church, Erdington of 1824; the Watt Memorial Chapel of 1826 at St Mary's Church, Handsworth; All Saints Church, Ladywood of 1834 (demolished); and the Bishop Ryder Church of 1836 (demolished). Rickman's longest-lasting influence on the course of the Gothic revival however was his book "An Attempt to Discriminate the Styles of English Architecture, from the Conquest to the Reformation"; the first study of Gothic architecture designed to guide architects towards historically authentic styles and the first to establish a convincing classification and chronology of English Gothic architecture, defining the four principal periods – Norman, Early English, Decorated and Perpendicular – that still frame the understanding of Gothic styles today.