For the provision of First Class carriages in the electrification project, First Class steam hauled cars were converted. The carriages were class _A__, of 59'9" length.
Conversion involved removal of gas lighting equipment ( gas lights, pipes, gauges, gas tank ) and the fitting of electric lighting circuit, globes and holders. As well two electric cables were fitted; one for the electric light supply and the other for the through cabling connections for train traction and auxiliary control.
First Class cars in electric service were coded AT, with a new number group. The AT numbers were: 1 - 5, 7 - 12, 14 - 18. Six cars were converted in 1919 and ten cars converted in 1921.
Between 1921 and 1923 the cars were recoded to _T__, retaining the same numbers.