The L class were designed to provide improved performance over the successful F class on faster passenger services and were built by the Avonside Engine Co.. All entered service in 1878 and were used on important passenger trains on the Auckland and Wellington Sections. Although the G class, designed with a similar purpose in mind suffered from poor adhesion, the L was more successful in terms of performance. They were used intensively and provided solid service, although they were not used on passenger services for long due to their small size.
NZR began an intensive programme of rebuilding older tank locomotives to attempt to extract improved performance. Parts from seven locomotives were used in this programme, being initially fitted with a leading bogie turning them into LA Class4-4-0T's then later with larger coal bunkers to 4-4-2T's. The remaining three unmodified locomotives were sold to the Public Works Department (PWD) in the early 1900s.
While all of the rebuilt L class had been officially withdrawn by 1939, the three unmodified locomotives sold to the PWD went on to have much longer careers. No. 507 (formerly 207 in NZR service) was sold to the Taranaki Harbour Board in 1931, and numbers 508 and 509 (formerly 208 and 219) were sold to Wilson's Portland Cement, an industrial plant south of Whangarei. All three ended up working at Portland until the 1970s, when they were around 95 years old. They were then all donated for preservation where all three remain operational.