The locomotives numbered 140 to 149 were designed by Massey Bromley and delivered by Hawthorn, Leslie & Co. in 1880 and 1881. They were 0-4-4T tank locomotives intended for branch lines where the class E10 with the same wheel arrangement was too heavy. Originally they had a steam brake for the locomotive only, but this was later replaced with the Westinghouse air brake.
As the rear bogie did not carry more weight than a driving axle, it was later replaced by a single trailing axle, what improved the weight distribution. All ten locomotives were rebuilt in this way between 1891 and 1897. When they needed new boilers, they got the same boiler as the E10 had received during rebuilding. 