| W24 Calbourne | |
| Designer: | William Adams |
| Builddate: | 1891 |
| Builder: | LSWR Nine Elms Works |
| Powertype: | Steam |
| Fueltype: | Coal |
| Fuelcap: | 1.5LT
|
| Watercap: | 800impgal |
| Whytetype: | 0-4-4T |
| Driverdiameter: | 583NaN3 |
| Trailingdiameter: | 373NaN3 |
| Length: | 30inchesft8.5inchesin (ftin) |
| Locoweight: | 48.4LT |
| Cylindercount: | Two, inside |
| Cylindersize: | 17×24 in (445×610 mm) |
| Boilerpressure: | 160psi |
| Tractiveeffort: | 17235lbf |
| Locale: | Great Britain |
| Operatorclass: | LSWR: O2 SR: O2 |
| Powerclass: | Isle of Wight: B BR: 0P |
W24 Calbourne is an example of the Adams LSWR O2 class 0-4-4T, which is based at the Isle of Wight Steam Railway. It is the sole survivor of its class.
One of 60 Adams O2 class 0-4-4Ts, it was built by the LSWR in December 1891 at Nine Elms locomotive works and numbered LSWR 209. It was based at Fratton before moving on to Exeter. It passed into Southern Railway ownership in 1923.
The locomotive was transferred to the Isle of Wight on 26 April 1925 as the island's locomotive stock needed major modernisation, it was re-numbered W24 and given the name Calbourne, after a village on the island. The locomotive was fitted with Westinghouse air brake equipment to allow it to haul island passenger carriages, and had an extension fitted to its coal bunker to increase its range of operation.
Calbourne remained on the island under British Railway ownership, and was retained after steam services ended, with W31 Chale, as a works engine for the Ryde to Shanklin line electrification, until withdrawal in March 1967 when electrification of the line was complete.
Calbourne was acquired by the Wight Locomotive Society in 1967 as the flagship locomotive of the Isle of Wight Steam Railway, which has been its permanent home ever since. Calbourne is the only surviving O2 locomotive, the remainder having been scrapped.
In 1967 the Wight Locomotive Society acquired Calbourne from British Railways and it spent its early years in Southern Railway Malachite Green with Sunshine lettering. After an overhaul in 1992 it was repainted in Southern Railway Maunsell lined Olive Green with an unmodified coal bunker. Calbourne was withdrawn in 2002 for overhaul re-emerging in 2010 in BR Standard Mixed-Traffic Black livery with red and white lining and the larger bunker re-fitted. It was later repainted into Southern Railway malachite green livery.