| GNR Class O2 | |
| Powertype: | Steam |
| Designer: | Nigel Gresley |
| Builddate: | 1918, 1921 – 1943 |
| Totalproduction: | 67 |
| Whytetype: | 2-8-0 |
| Uicclass: | 1'Dh3 |
| Leadingdiameter: | 2feet |
| Coupleddiameter: | 4feet |
| Length: | 63feet |
| Width: | 8feet |
| Height: | 12feet |
| Locoweight: | 74.1LT78.65LT |
| Tenderweight: | 43.1LT52LT |
| Fueltype: | Coal |
| Firearea: | 27.5square feet |
| Diameterinside: | 5feet or 5feet |
| Boilerpressure: | 1802NaN2 |
| Totalsurface: | 2032square feet |
| Superheaterarea: | 430.5square feet |
| Cylindercount: | Three |
| Cylindersize: | NaNx |
| Valvegear: | Gresley conjugated |
| Valvetype: | 80NaN0 piston valves |
| Tractiveeffort: | 36740lbf |
| Powerclass: | BR: 8F |
| Fleetnumbers: | GNR: 461, LNER: 3921-3987, BR: 63921-63987 |
| Locale: | Eastern Region |
| Withdrawndate: | 1948, 1960 – 1963 |
| Disposition: | All scrapped |
The Great Northern Railway (GNR) Class O2 was a class of three-cylinder 2-8-0 steam locomotives designed by Nigel Gresley for freight work and built by the GNR from 1921. Further examples were built by the London and North Eastern Railway (LNER) from 1924.
The LNER created four subclasses: [1]
The first models of this class were designed and built under GNR ownership, the first locomotive, 461, was built in May 1918. A batch of ten further O2s was built by the North British Locomotive Co. in 1921.
Fifteen more O2s were built immediately after the Grouping in 1923. Sixteen more were delivered in 1932 and 1933. Wartime requirements led to the construction of 25 from 1942 to 43 in three batches.
All 67 locomotives passed to British Railways (BR) in 1948 and were given BR Numbers 63921–63987, but 63921 (which was the prototype 461, LNER 3921) was quickly scrapped. They served all across the former LNER from Stratford through East Anglia into the East Midlands, primarily hauling coal and iron ore trains. By winter 1955/56, they had all gravitated to Doncaster (36A - 35 locomotives), Grantham (35B - 14 locomotives) and Retford (36E - 17 locomotives). By winter 1962, they were down to 52 locomotives still in much the same locations, the following having been scrapped: 63929/34/44/47/50-55/57-59/70.
By the end of 1963, all members of the class had been scrapped.