The Arts and Crafts Movement marked a golden age of Birmingham architecture, placing the city at the forefront of English architecture at a time when English architecture was leading the world. Its influence was international: Lethaby was the most important architectural theorist of the whole movement, and built over half of his work in Birmingham or for Birmingham clients, while the buildings of Birmingham architects such as William Bidlake and William Alexander Harvey were to feature prominently in Herman Muthesius's 1905 book "The English House", which was to be revolutionary in its introduction of the Arts and Crafts philosophy into Germany, and a pivotal influence on the later birth of the modern movement.