NER Class R LNER Class D20
1907-built class R 2387, at Gateshead in 1954
Type and origin Power type Steam Designer Wilson Worsdell Builder NER Gateshead Build date 1899-1907 Total produced 60
Specifications Configuration: ​  • Whyte 4-4-0 Gauge 4 ft 8 1⁄2 in (1,435 mm) standard gauge Leading dia. 4 ft 0 in (1.219 m) Driver dia. 6 ft 10 in (2.083 m) Wheelbase 23 ft 9 in (7.24 m) engine 12 ft 8 in (3.86 m) tender 45 ft 10+3⁄4 in (13.989 m) total Axle load 19.8 long tons (20.1 t; 22.2 short tons) Loco weight D20/1: 54.1 long tons (55.0 t; 60.6 short tons) D20/2: 55.45 long tons (56.34 t; 62.10 short tons) Tender weight 41.2 long tons (41.9 t; 46.1 short tons) Total weight D20/1: 95.3 long tons (96.8 t) D20/1: 96.65 long tons (98.20 t; 108.25 short tons) Fuel type Coal Firebox:  • Firegrate area 20 sq ft (1.9 m2) Boiler 4 ft 9 in (1.45 m) diameter Boiler pressure 200 psi (1.4 MPa) later reduced to 160 psi (1.1 MPa) Heating surface 1,318.7 sq ft (122.51 m2)  • Tubes 638.7 sq ft (59.34 m2)  • Flues 292 sq ft (27.1 m2)  • Firebox 139 sq ft (12.9 m2) Superheater: ​  • Heating area 204 sq ft (19.0 m2) Cylinders two inside Cylinder size 19 in × 26 in (483 mm × 660 mm) Valve gear Stephenson
Performance figures Tractive effort 17,025 lbf (75.73 kN) later reduced to 15,567 lbf (69.25 kN)
Career Operators North Eastern Railway, London and North Eastern Railway, British Railways Power class BR: 2P Retired 1943-1957 Disposition All scrapped

The NER Class R (later, LNER Class D20) was a class of 4-4-0 steam locomotive, designed by Wilson Worsdell for the North Eastern Railway. They passed to the London and North Eastern Railway (LNER) in 1923. In 1936, some were rebuilt with long-travel piston valves and classified D20/2. The unrebuilt locomotives were re-classified D20/1.

• D20/1 Archived 2016-12-20 at the Wayback Machine Rail UK
• D20/2 Archived 2016-12-20 at the Wayback Machine Rail UK
• The W.Worsdell Class D20 (NER Class R) 4-4-0 Locomotives LNER Encyclopedia