The Ceylon Government Railway classes B1–B6, formerly designated as the NOA class before the reclassification of 1937, were several classes of 4-6-0 steam locomotives of similar designs operated on the Ceylon Government Railway (CGR) for service on the Main Line. As of 2025, only certain locomotives of the B1 and B2 classes survive into preservation.^[1][2]

Ceylon Government Railway B1
B1A No. 251 "Sir Thomas Maitland" hauling the Viceroy Special
Type and origin Power type Steam Builder Beyer, Peacock & Company (B1, B1A/C) Armstrong Whitworth (B1B) Robert Stephenson & Company (B1D/E) Build date 1927-1930 (B1 to B1C) 1945 (B1D) 1948 (B1E) Total produced 49
Specifications Configuration: ​  • Whyte 4-6-0 Gauge 5 ft 6 in (1,676 mm) Driver dia. 53.5 in (1.359 m) Length 58 ft 7.5 in Axle load 13.50 long ton (B1 to B1C) 13.40 long ton (B1D/E) Loco weight 52.30 long ton (B1 to B1C) 53.05 long ton (B1D/E) Tender weight 42.55 long ton (B1 to B1C) 45.55 long ton (B1D/E) Fuel type Coal, Oil Water cap. 3300 gal Boiler: ​  • Diameter 4 ft 8 in Boiler pressure 160 lb/sq.in Cylinders 2 Cylinder size 18.5 in × 26 in (470 mm × 660 mm) Valve gear Walschaerts
Performance figures Tractive effort 22,620 lbf
Career Operators Ceylon Government Railway Nicknames Governor Class Disposition Two preserved, remainder scrapped

The Class B1 locomotives were the last and most modern of these six locomotive classes to be constructed.^[3][4] A total of forty-nine were built for the Ceylon Government Railway from 1927 to 1948. This class had five subclasses apart from the standard model, namely A, B, C, D and E. These locomotives are also known as the Governor Class, as most class members were named after governors of British Ceylon. In 1936, class member no. 242 Sir Edward Paget was streamlined, but the streamlining was later removed in 1937.^[1] In the 1950s, some members of the class were converted to burn oil instead of coal.

Only two members of the class, No. 251 Sir Thomas Maitland and No. 340 Sir Frederick North, have survived into preservation.^[5] Both are currently operational and are used to haul the Viceroy Special, a chartered excursion train operated by J. F. Tours.

Ceylon Government Railway B2
B2B No. 213, the only surviving member of the class
Type and origin Power type Steam Builder Stephenson (B2) Vulcan (B2A/B/C/D) Kitson (B2E) Build date 1920-1921 (B2) 1925-1926 (B2A/C/D) 1922 (B2B) 1915 (B2E) Total produced 35
Specifications Configuration: ​  • Whyte 4-6-0TT Gauge 5 ft 6 in (1,676 mm) Driver dia. 53.5 in (1.359 m) Length 53 ft 2 in Axle load 13.50 long ton Loco weight 54.85 long ton Tender weight 32.50 long ton Fuel type Coal Water cap. 2400 + 400 gal (SIde tanks) Boiler: ​  • Diameter 4 ft 8 in Boiler pressure 160 lb/sq.in Cylinders 2 Cylinder size 18.5 in × 26 in (470 mm × 660 mm)
Performance figures Tractive effort 22,620 lbf
Career Operators Ceylon Government Railway Disposition One preserved, remainder scrapped

A total of thirty-five members of this class were produced for the Ceylon Government Railway. The Class B2 also had various subclasses excluding the original from A to E.^[1]

Only one member, No. 213, survives into preservation. It is also maintained in working order so as to haul the Viceroy Special.^[5]

Reference: ^[1]

Reference: ^[1]

Reference: ^[1]

These were the first 4-6-0 locomotives to operate in Ceylon. They have a unique combination of both tenders and side tanks, although the side tanks were mainly to increase the adhesive weight over the driving wheels.

The main line of the Ceylon government railways starts at Colombo and originally terminated at Nanu Oya station.Beyond Nawalapitiya the line climbs at a constant 1 in 44 gradient all the way to Nanu Oya. This would have been beyond the capacity of the 4-4-0s then in service at the time the main line was extended above Nawalapitiya. Thus these new 4-6-0TT locomotives were known as the Nanu Oya class after the route on which they were intended to operate. Reference: ^[1]

• Smith, Jonathan. "Ceylon Govt. Rly. 66in gauge steam locomotives". The terminal: Standard steam locomotives. Iowa State University. Retrieved 31 August 2025.