Mark Ovenden is an expert on typefaces. In this one-off BBC Four documentary he focuses on two fonts in particular that have been cornerstones of design in this country. One of these is Johnston, which is the font that was used originally on the London Underground and is now used throughout London’s transport network. The other is Gill Sans, the font that was used by both the BBC and Penguin Books. The creator of the former, Edward Johnston, was the man who taught Eric Gill, who made the latter. Ovenden delves into the history of both the types faces and their impact. Two Types: the Faces of Britain is on BBC Four at 21.00.