Experimental Locomotives on the LNER
Although the term 'experimental' could be used for a wide range of locomotives that introduced new technologies such as piston valves and superheaters, here it refers to locomotives which were intended to test more revolutionary concepts.
The LNER was open to a number of outside experiments, and hosted trials of locomotives produced by Kitson & Company; the North British Locomotive Company; and Armstrong Whitworth Company. It also developed the water-tube W1 'Hush Hush' with Yarrow & Co.
| Locomotive | Builder | Built | Withdrawn | Type |
| Reid-MacLeod | North British Loco. Co. | 1924? rebuild | ~1940 | Steam Turbine |
| Graz 0-4-0 | Simmerung-Graz-Pauker | 1924 | ? | Diesel Hydraulic 0-4-0 |
| Kitson-Still | Kitson & Co, Leeds | 1927 | 1935 | Experimental steam-diesel hybrid |
| W1 'Hush-Hush' | LNER / Yarrow | 1929 | 1936 (rebuilt) | High Pressure Water Tube Boiler |
| 1-Co-1 | Armstrong Whitworth | 1933 | 1934 | Experimental diesel-electric |
| MetroVick Railcar | Metro Vick Cammell | 1937 | 1951 (re-gauge) | Diesel Railcar |
| DS1173 | Drewry/Vulcan Foundry | 1947 | 1968 | Diesel Mechanical 0-6-0 |