 In 1846 Blacket, who was seen by the committee to have a greater grasp of architectural principles and design than Hume, was appointed to replace him as architect of the cathedral.While the cathedral was under construction, a temporary wooden cathedral was erected, and one of Blacket's first jobs was to create a stained-glass window for it.Being unable to acquire coloured glass, he painted plain glass and fired it, using part of the crypt beneath St James, King Street, as his studio.