According to the following website (from Argentina?) the 237s were made from 1968-1972.
http://www.servirem.com.ar/nueva.html
Gary
May 2010
Hello Terbear,
They started making the 237 back in 1965, Singer continued on with that model for years in slightly different shapes and colours and sometimes giving them names such as Fashion Mate, originaly made in Italy but also made in various factories through out the world as time went on.
Ken