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Northern Ireland Railways 450 Class
8458 departing City Hospital in 2009.
In service	1985–2012
Manufacturer	British Rail Engineering Limited
Family name	BR Second Generation (Mark 2 and Mark 3)
Entered service	1985–1987
Scrapped	2012–2017
Number built	9 sets
Number scrapped	8 sets
Formation	3-car sets (DM-T-DT)
Fleet numbers	Originally: 451–459, Now: 8451–8459
Capacity	184 seats
Operators	Northern Ireland Railways
Lines served	At time of withdrawal: Belfast-Larne Coleraine-Portrush Formerly: Belfast-Bangor Belfast-Newry
Specifications
Maximum speed	75 mph (121 km/h)
Prime mover(s)	English Electric 4SRKT
Safety system(s)	AWS, TPWS
Track gauge	1,600 mm (5 ft 3 in)

The 450 Class is a type of diesel multiple unit (DMU) passenger train formerly used by Northern Ireland Railways. They were affectionately nicknamed 'Thumpers' and 'Castles' (also known as the Castle Class) by rail enthusiasts.

In the mid-1980s, Northern Ireland Railways was in the process of upgrading its rolling stock. Having already purchased three new locomotives, it then proceeded to purchase replacements for its 70 Class diesel multiple units. A total of nine three-car trains were constructed by British Rail Engineering Limited between 1985 and 1987, intended to supplement the existing 80 Class DMUs then in service. The trains were constructed using underframes of existing Mark 1 coaching stock, altered to using 1,600 mm (5 ft 3 in) gauge and new Mark 3 bodyshells with powered sliding doors. Because of this, they bore a strong resemblance to the British Rail Class 150, British Rail Class 210, British Rail Class 317, British Rail Class 318 (especially prior to its refurbishment) and British Rail Class 455, as they also use the Mark 3 bodyshells with end doors. These were combined with refurbished power units and traction motors from the withdrawn 70 Class units (there were only eight 70 Class units available to be salvaged, so the equipment for the ninth train came from a withdrawn Class 80 train, powercar 88 that was damaged at a collision at Hilden).

The power cars of the 450 Class units were named after various Northern Irish castles.^[1] They entered service in a cream, orange, and red livery, before adopting the blue and silver livery later.

On Thursday 9 March 1995, a 450 Class train was used to form a royal train when Queen Elizabeth II officially opened the Dargan Bridge, composed of two cars from 455 coupled to two cars from 459.

The 450 Class operated on the same principle as the prototype Class 210 DMUs on the British network, in that they consisted of a single power car containing the traction and generating equipment (numbered 45x), an intermediate trailer car (numbered 79x) and a driving trailer (numbered 78x) as permanently formed 3 car sets. An additional "8" was added to the start of all the cars so that they could be used by Translink's computer system.^{[citation needed]}

In 2005, the entire fleet underwent an extensive refurbishment to bring them up to a similar standard to the newly introduced 3000 Class units, enabling them to remain in service for at least another 5 to 7 years.^{[2][non-primary source needed]} This took them up to the point where they became "life-expired."^{[3][non-primary source needed]}

In 2011, the entire 450 Class fleet, together with the remaining 80 Class units, was listed by NI Railways for disposal.^{[4][non-primary source needed]} The first of the trains was broken up and scrapped in April 2012.^[5]

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The entire 450 Class fleet was withdrawn from service in 2012, following the arrival of enough 4000 Class units to displace the 450 units serving the Larne Line and Portrush branch. Eight out of the nine units have been cut up for scrap. The sole remaining example has been purchased for preservation by the Downpatrick and County Down Railway.

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Originally they operated on suburban services on the Larne and Bangor Lines, occasionally serving the Newry Line as well, with occasional appearances on the Derry line.

With the arrival of the Class 3000 trains in 2004, the 450s still had to be retained, as the 3000s were only a like-for-like replacement of the old Class 80 units. By the year of their withdrawal, the 450 Class units had mostly been relegated to weekday services on the Larne Line and the Portrush Line shuttle, however at weekends there were enough Class 3000 trains to operate these services.

The gradual entry into service of the Class 4000 trains in 2012 saw the 450 Class units each displaced by a new Class 4000 unit as one became available, until they were all finally withdrawn.

One example of the class has been preserved, by the Downpatrick and County Down Railway. Unit 458 Antrim Castle was moved by road from York Road Depot, Belfast, over the weekend of 27–28 September 2014. During a two-day operation, the set was split into Driving Trailer, Intermediate and Power Car at Belfast and then, one-by-one, the carriages were taken by lorry to Downpatrick where they were reassembled. The Driving Trailer arrived on 27 September 2014, with the Intermediate and Power Car arriving the following day. The complete 458 successfully ran under its own power on 11 October 2014, and one week later on 18 October 2014, made a surprise appearance at the Irish Traction Group's Diesel Gala—the first time the unit had carried passengers since withdrawal by NIR in 2012.

The DCDR stated that it planned to convert 458 into a standby buffet train. This was completed in summer 2018, with the railcar usually being stationed at Inch Abbey station during the summer months.

In Autumn 2021, 458 was used in the filming of a season 3 episode of Derry Girls, with DCDR standing in for the Belfast–Derry and Coleraine–Portrush lines.^[6][7]

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