Speed exhibited a mix of Italian landscape, allegorical subjects and portraits at the Royal Academy and elsewhere in a long career; he also taught, notably at Goldsmith's, and wrote an influential manual, The Practice and Science of Drawing (Seeley, Service and Co., 1913) which is still used by students today. In it he wrote:

'A delightful medium that can be used for either pure line work or a mixed method of drawing, is red chalk. This natural red earth is one of the most ancient materials for drawing. It is a lovely Venetian red in colour, and works well in the natural state, if you get a good piece ... Red chalk when rubbed with the finger or a rag spreads evenly on paper, and produces a middle tone on which lights can be drawn with rubber or bread ... You can continually correct and redraw in this medium by rubbing it with the finger or a rag, thus destroying the lights and shadows to a large extent, and enabling you to draw them again more carefully. For this reason red chalk is greatly to be recommended for making drawings for a picture where much fumbling may be necessary before you find what you want. Unlike charcoal, it hardly needs fixing, and much more intimate study of the forms can be got into it. Most of the drawings by the author reproduced in this book are done in this medium. For drawings intended to have a separate existence it is one of the prettiest mediums. In fact, this is the danger to the student while studying: your drawing looks so much at its best that you are apt to be satisfied too soon.'