This 0-6-0DH locomotive (Builder's number 3767 of 1983) was built by Baguley-Drewry of Burton-on-Trent, for an order from Mozambique which was subsequently cancelled. INA acquired her nickname from the Mozambique company's Instituto Nacional do Acucar (National Sugar Institute) initials on her cab side.
The locomotive did trials on the Ffestiniog Railway in 1985 but was found to be too large to fit within the loading gauge. Subsequently, the company purchased her in 1988 from the Bredgar & Wormshill Light Railway in Kent in part exchange for The Peckett. She was altered at Boston Lodge, with a differently-profiled cab. Fitted with RAF waggon couplings and no vacuum brakes, she is used by the Permanent Way Department. Her 180hp CAT engine, fully enclosed cab and seats make a nice change from other works engines. She has a HARLECH CASTLE nameplate on one side and CASTELL HARLECH on the other.
In 2009 she suffered from a series of failures and entered Boston Lodge Works for a major overhaul in August. This has included re-profiling the wheels and the fitting of a new gear box.
During the winter of 2011, Harlech's electrics were rewired due to a series of failures over the previous year. During the overhaul it became apparent that other components had failed and she was fitted with a new radiator and a new turbo. The engine was tested and passed by an engineer from Cat, the manufacturer.