Owl is an 0-4+4-0 geared locomotive based on a 1920's design by the Avonside Engine Company Ltd (of Bristol). She is a twin cylinder 'V' type engine with cylinders 5" in diameter and 8" stroke and is fitted with Stephenson valve gear. This drives through centrally mounted carden shafts to enclosed 1.5 to 1 enclosed bevel reduction gearboxes on each bogie. The final drive is by chain to each axle. Similarly to the other locomotives Owl is fitted with a welded steel saturated steam boiler with a working pressure of 180lbs. The fire grate area is 3 square feet and was fitted with a simple gas producer combustion system from new. The locomtive has a tractive effort of 3,279lbs. Owl entered service on the railway in late 1999.