Ratio Scale Models was started in 1950 by Jack and Dev Webster, producing fine coach kits made from sheet plywood pressings in Chorleywood, Hertfordshire. They commenced manufacturing plastic kits in 1959 and the name was changed to Ratio Plastic Models. The factory was moved to Goring-on-Thames in 1961, and to Sturminster Newton in 1972. As the range continued to grow, they moved to larger premises in Buckfastleigh in 1986. Ratio was sold to PECO in 1996; production now takes place at a new factory in Buckfastleigh, along with the Wills and Parkside ranges.