in 1970 clarke enrolled in the architectural stained glass course at north devon college of art and design, where he went on to receive a first class distinction in their diploma in design in 1972. in 1971, aged 17, he received a commission for a series of windows in the grade ii* listed southcott barton, a 17th-century residential home, through a chance meeting with jeremy thorpe, then member of parliament for north devon, and the following year he received his first ecclesiastical commission, for a memorial window in preston parish church. in august 1972, he married his fellow art student liz finch, the daughter of a local vicar, opened a stained glass studio in preston, and began to take on work including painting restoring, designing lamps, repairing damaged ecclesiastical glass, as well as working independently as a painter. this was followed by a commission for a new window for coppull church, lancashire, in 1973, and further secular stained glass commissions, for which he painted, fired, leaded, assembled and installed the windows and panels himself, transporting them on a local bus. further local ecclesiastical commissions followed.