A pre-Worboys Committee 'Major Road Ahead' traffic sign. The red triangle in a ring sign was mounted with warning plate cautioning drivers that they need to give way at the next junction. This sign design was phased out in 1944, in order to match the Vienna Convention on Road Signs and Signals alternate stop sign design.
Report of the Departmental Committee on Traffic Signs - 1933.
Ministry of Transport (1919 - 1941)