The 116 was extensively used in South Wales, being belatedly introduced on 2 December 1957 in the Cardiff Valley region. Originally intended to be introduced in September, a lack of vehicles caused the delay into service. They were housed at Canton depot. Just as in the Birmingham region, the new trains were heavily advertised. The units were used for the next 30 years almost exclusively in the South Wales area, but did occasionally work services to Bristol and Bath.
