The effect, which occurs thanks to a conducting fluid in which the yarns were dipped, could be put to use in motors much thinner than a human hair.

BBC: Nanotube yarns twist like muscles

Mr Olej, of Bearsden, and Mr Starrett, of Port Glasgow, are said to have then poured lighter fluid onto the carpet and lit it causing a fire to take effect in the house.

BBC: Murder jury shown images of dead pensioner John McCulloch