The Córas Iompair Éireann 201 Class was a class of 34 diesel electric locomotives manufactured by Metropolitan-Vickers at their Dukinfield Works in Manchester. They were a smaller, lighter and less powerful version of the 001 Class and were originally intended for branch line passenger and freight (mixed traffic) duties. They were introduced in 1956 and, although their duties changed over the years, were in regular service on the Irish railway network until the mid-1980s. Six were sold to Northern Ireland Railways (NIR) in 1986.
Service history.
Unfortunately, these locomotives suffered from two distinct problems: 
Replacement engines:
Because of the problems with the Crossley engines attempts were made to fit the locomotives with more suitable equipment. Between 1965 and 1980, Maybach MD650 engines of were fitted in Nos. 233 and 234. From 1969, however, a permanent solution was found by fitting the entire class with General Motors engines, a similar process that was previously undergone by the 001 Class). 
 New Duties:
From 1969 the class were given new duties, being partnered with former 2600 class diesel multiple units converted to four-car push-pull carriage rakes to operate the suburban services around Dublin. In 1984 the Dublin suburban lines over which they worked were electrified and new electric multiple units known as the 8100s operated the newly named Dublin Area Rapid Transit (DART) system.
The first member of the class to be withdrawn was No. B201, being bomb damaged in 1973. The remaining members of the class, except for the six sold to NIR, were withdrawn over the two years following the opening of the DART system having completed 30 years service for their operators.
Numbering.
When built, these locomotives were numbered C201-C234, and as locomotives were re-engined, they were renumbered B201-B234 to reflect their increased power. However, the prefix letter was later dropped.
Livery.
Over the years the class has carried six different liveries. When introduced they were painted an all-over silver livery which unfortunately dirtied quickly and was not a good advert for dieselisation. This was followed by all-over CIÉ green livery with a thin lighter green band on the lower panels, giving a uniform appearance to the train sets. In the next change black became the base colour with just a white relief around the top panel, which opened to a squared-off 'V' between the cab windows. Some locomotives received large yellow panel to the cab fronts to aid visibility. With the adaptation by CIÉ of its "Black and Tan" scheme in the mid-1960s, the locomotives received this livery with a white line at roof level to match the coaches. The last CIÉ livery was of Golden Brown with a very broad black band covering the upper panels at the level of, and as wide as, the cab windows.
Those locomotives sold to NIR carried their blue livery.
NIR use.
After withdrawal from CIÉ, six locomotives were sold to Northern Ireland Railways, which designated them 104 Class. They entered traffic for NIR in 1986–1987, except 105. Originally, CIÉ 224 was intended to become 105, but it was subsequently rejected by NIR and replaced by 218, which only entered traffic in 1991. 224 was left stored with NIR until it was scrapped in January 1996.
Of those that entered service, some had very short lives working for their new owners. They were stored as soon as any problems arose (e.g. a seized engine or traction motor), and the whole class was formally withdrawn in 1993 (107/109) or 1995 (the others). The locomotives involved, their new numbers and their withdrawal are set out below:
Notes and references.
Notes.
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References.
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