This is a drawing from 1902 by the British architect William Richard Lethaby, made soon after the announcement of an architectural competition for Liverpool Cathedral. The drawing reveals an intensely creative moment at the very beginning of the design process. As if fearful of losing his inspiration, Lethaby has grabbed the nearest sheet of paper - which happens to be a used envelope - and covered it, front and back, with designs for the cathedral. The ‘back of the envelope’ sketch is a term often used to describe the designer’s first ideas, and this drawing shows exactly where the expression originates. Such drawings are greatly valued because they show the creative vision in its purest form, before the design becomes compromised by budgets, clients and manufacturing methods. Indeed, Lethaby’s final designs for the cathedral incorporate the same Byzantine features and reinforced-concrete structure suggested in these first sketches. Lethaby failed to win the competition.

Lethaby was a founder of the London County Council Central School of Arts and Crafts, and professor of design at the Royal College of Art, London. He was also an influential writer on architectural subjects.