Married couple Pat Ashforth and Steve Plummer have been knitting and crocheting mathematical images and objects fore more than two decades.
In 1996 two British maths teachers active on an internet knitting forum were asked by a US yarn firm to design it an afghan.
We were sent into a panic! We had no idea what an afghan was! remembers Pat Ashforth, who with partner Steve Plummer is known in the crafts community for maths-inspired knits.
The couple soon discovered that an afghan was a knitted or crocheted blanket or throw. They produced four designs for the US firm, and it began a journey that has defined the rest of their lives.