[6] Robert Stephenson and Company built seven PT class locomotives for the South Indian Railway (SIR) in 1936, bearing works numbers 4114 to 4120.

[2] This batch differed significantly from the earlier F and FS classes (which correlate to the original BESA design with internal valve gear) by being fitted with outside cylinders.

A larger standard boiler with a diameter of 5 ft 1 1⁄4 in (1556 mm) was developed for the PT, which was also listed as a variant in the third BESA report for the SP and SG class locomotives.

[9] Alternatively, the existing boilers from the SP and SG classes could also be used, provided that the weight of the locomotive was altered in accordance with the requirements of the report.

[5] In contrast to the design recommendations of the BESA report, the SIR locomotives were fitted with external Lentz rotary valve gear.