This Bedford CA is based on the 15 cwt series which was produced between 1959 and 1969.
The Bedford CA had a 90 inch wheelbase, quite small by today's standards, so they launched a 102 inch version which was designated the CAL, hence the CA became known as the CAS.
The Unigate name originated in 1959 when United Dairies and Cow & Gate merged. The 1940's saw the emergence of the electric milk floats as the use of horses was phased out, by the 1960's petrol vehicles were becoming more popular.
The Bedford CA chassis found itself used as the basis for a succession of motor commercial vehicles such as this 1965 Unigate milkfloat.