Sign language

Margaret Calvert revolutionised how Britain looked and her brilliantly clear designs are still used today. We meet the genius who kept drivers safe

- Catherine Slessor

Stuffed with a barrage of road signs, artful modernist chairs and all the tools of her trade, Margaret Calvert's studio occupies the ground floor of her house in Islington, London. She still draws by hand, using coloured pencils, ink pens and gouaches, echoes of a simpler time when there were neither computers nor gazillions of Pantone colour options.

"There was also no such thing as graphic design back then," she says. "It was just called commercial art." Only a handful of graphic designers have had a typeface named after them, but Calvert has been inducted into the graphic equivalent of Mount Olympus. The Calvert typeface can be appreciated on the Tyne and Wear Metro. The black M on a yellow background has become a civic and graphic landmark across the north-east of England.

Calvert is a contemporary version of a slab serif. It has been described as having "vitality and elegance, avoiding the stiff and mechanical".

The same might be said of the woman herself.

She drew from a very early age. "I can remember drawing on the floor on huge sheets of paper, not with crayons, just with a pencil," she recalls. She especially enjoyed life drawing.

"I think that's why I'm so fascinated by typefaces and lettering, because I think of a letter's form as if it were a skeleton fleshed out in different ways."