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London & North Eastern Peppercorn class A2

Great Britain 1947 15 produced
60532 “Blue Peter” in April 2024 at Kidderminster BWard 1997 CC BY 4.0

The Peppercorn class A2 was a Pacific locomotive designed in the last years of the LNER and inspired by the Thompson class A2/2. Like Thompson's locomotives, it had three cylinders and 6 ft 2 in (1,880 mm) drivers, as opposed to the 6 ft 8 in (2,032 mm) of other LNER Pacifics. This made it suited for lines with inclines, like branches of the East Coast Main Line and lines in Scotland. The first locomotive, No. 525, was built in 1947 at Doncaster and delivered to the LNER in December. It was named “A.H. Peppercorn” after its designer and last Chief Mechanical Engineer of the LNER. The next 14 locomotives were directly delivered to British Railways and named after race horses.

Compared to the A2/3, the new A2 had its outside cylinders moved towards the front and had lost its Kylchap exhaust. The cylinders still measured 19 inches in diameter and 26 inches in stroke and the boiler pressure was unchanged at 250 psi. This resulted in a starting tractive effort of 40,430 pounds. No. 60539 “Bronzino”, the last one, was delivered with a Kylchap exhaust. In 1949, five more were also fitted with this type of exhaust. In comparison with the bigger-wheeled Gresley Pacifics with smaller grates, they had a higher consumption when running at high speeds.

British Railways put them in power class 8P7F, what meant that they could also be used like a class 7F freight locomotive if needed. In England, all were withdrawn in 1962 and 1963. In Scotland the last ones were only withdrawn in 1966. The only one that was preserved was 60532 “Blue Peter”. It was steamed up for the first time again in 1974 and received its main line certificate in 1992 after a second restoration. The main line certificate expired in 2001, followed the boiler certificate that expired in 2002. A larger overhaul started in 2015 and in 2024, it became operational again.

60530 “Sayajirao” in April 1966 at Dundee Tay Bridge Station Ben Brooksbank / CC BY-SA 2.0

Technical data

General

Built
1947-1948
Manufacturers
Doncaster
Wheel arrangement
4-6-2 (Pacific)
Gauge
1,435 mm (Standard gauge)

Dimensions and weights

Length
21.65 m
Wheelbase
10.47 m
Total wheelbase
18.44 m
Service mass
102.6 t
Total mass
163.1 t
Rigid wheelbase
3.96 m
Axle load
22.4 t
Water capacity
22,731 l
Fuel capacity
9.1 t (coal)

Boiler

Grate area
4.645 m²
Firebox surface
22.761 m²
Tube heating surface
205.966 m²
Evaporative heating surface
228.728 m²
Superheater surface
63.174 m²
Total heating surface
291.9 m²

Power plant

Driver diameter
1,880 mm
Boiler pressure
17.2 bar
Expansion type
simple expansion
Cylinders
three, 483 x 660 mm

Power

Power source
steam
Estimated power
2,237 kW (3,041 PS)
Starting effort
179.8 kN

Calculated values

Optimal speed
76 km/h
Power-to-weight ratio
21.8 kW/t
Heating Surface Equivalent
468.9 m²
Cylinder volume/HSE
1 : 772.91
Tractive force/Heating surface
1 : 12.87
Grate area/Heating surface
1 : 62.84
Firebox/Tube surface
1 : 9.05
Total/Superheater
1 : 3.62

Topics

  • steam locomotive
  • express
  • Arthur Henry Peppercorn
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Last changed: 03/2026

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