 In 1929 further carriages were deemed surplus to electric fleet requirements, and carriages 6, 19, 20, 21, 24, 26, 43, 39, 100, and 101T were converted back to B type country carriages, however instead of regaining their former numbers, they became 162-171B, these being the next available after the highest numbered B carriage at the time.A further re-classification of First class T cars was made in 1940, when a shortage of second class accommodation on the suburban system became evident, the situation being exacerbated by the Second World War and its associated petrol rationing.Fourteen of the swing-door trailer fleet were re-coded to BT, although keeping their T fleet numbers.