A key driver of the changed construction method was to overcome the serious corrosion problem point in the Mark 1 at the base of the body, where it was attached to the underframe.The Mark 2 coach was one of the mainstays of the InterCity network, but new rolling stock introduced in the post-privatisation era has resulted in most being withdrawn.Since their withdrawal from most main line duties, Mark 2 coaches have played an increasing role on private rail tours, charter trains, and on heritage railways.These luxuriously appointed first class carriages had several unusual features, such as inward opening doors and some interior walnut panelling.They were reintroduced in September 2006 to provide extra capacity on the Portadown to Belfast (Central) service, making one trip every morning, hauled by a Class 111 locomotive.The RPSI bought the eight withdrawn Gatwick Express Mark 2 coaches and generator van from NIR, which are currently (2017) in store at Dundalk and Whitehead.The DBSO entered preservation at the Downpatrick and County Down Railway on 27 September 2014, having never carried a passenger in NIR service or having left York Road depot by rail.With air conditioning as a principal feature they became known as "AC Stock" and ran on type B4 bogies, with vacuum brakes.The generator van contained two engine/generator sets, each supplying 220/380 V 50 Hz AC to two separate electrical buses in the train.Air conditioning output power would then be halved, but all other loads including cooking, lighting and battery charging would continue to be supplied.Most of them (104) operated in Auckland, classified SA (81) and SD (23), in push-pull commuter trains, with three to five SA carriages, an SD driving carriage (similar to the original Mark 2 DBSOs), and a DC class (four- and five-car) or DFT class (six-car) diesel-electric locomotive.Auckland has since replaced its entire suburban fleet with the purpose-built New Zealand AM class electric multiple unit.There are also six SE class carriages, which were used with electric locomotives on Wellington commuter services between 2008 and 2011 as a temporary measure until new EMUs were delivered.Mainline Steam also own four refurbished carriages, classified ML, which are based in Plimmerton (north of Wellington) and are used for its steam-hauled excursions.Following a decision to electrify Taiwan's busy West Coast Main Line, thirteen 5-car electric multiple units based on the Mark 2 design were built by BREL in York for the Taiwan Railway Administration in 1976, but following problems with the electrical equipment and excessive weight could not enter service until 1979 following the completion of remedial works.2Bs covering both the BR and NIR variants was announced by Irish Railway Models and its British-outline arm Accurascale in late 2021.