The AC group were numbered 1 to 143.
Cars AC 1 - 82 were ex ADAD in the 1910 recoding.
Cars 83 to 143 were converted from _A__ cars between 1911 and 1913. Conversion included lengthening the body from 45' to 59'9" and the fitting of a van section at one end of the car.
Between 1919 and 1923 the cars were modified for electric traction.
Some cars became ACD_ or _D__.
Most cars became ACM_ or _M__.
In 1923 the swing door conversion project was suddenly stopped. Some of the cars were in various stages of conversion to M or D when the work stopped. The cars were stripped of electrical fittings and returned to steam hauled service.
The cars remaining were AC 7, 26, 30, 38, 40, 42, 45, 47, 51, 55, 57, 58, 64, 66, 67, 69, 71 and 72.
The cars stayed in service as 'AC' until 1927 when they were progressively relettered to _BC_ between 1927 and 1930. AC 64, 66, 67, 69, 71, 72 became BC 1 - 6.
Between 1929 and 1930 the remaining cars 7, 26, 30, 38, 40, 42, 45, 47, 51, 55, 57, 58 became BC 7 - 18.
Some of these part converted cars were still in service in the 1950's. The cars were eventually removed from service and were converted to _WW_ works sleepers.