The answer is Spitfire
No. 34066 was the locomotive involved in the Lewisham disaster of 1957, when the driver overran signals and collided with the Charing X to Hayes EMU, the accident demolished the Nunhead flyover and a third train fell onto the wreckage of the first two.
The other Spitfire was on the Redruth & Chasewater railway, when the line changed from horse to steam traction, the line's two four coupled locomotives had to work hard, scattering ash and cinders. as a result, a thatched cottage was in danger of being set alight, the railway was persuaded to demolish it and rebuild it at a safe distance from the line. Hence the name of the third locomotive.
I could have reworded the question as Spitfire was involved in the only fatal accident on the R&C. A couple of wagons would be left by a works which had no siding, on return, they would be propelled back to Devoran. The road had been relaid, but the level crossing flangeways were not cleared, with the result that the wagons derailed and the brakeman received injuries which were fatal. However, many minor lines never had a single fatlity or serious injury - the only one I can think of involving gross negligence was that on the Campbeltown and Machrihanish.
I'm declaring open floor