NCC Class A1

The Class A1 locomotives were rebuilds of the Class A "Heavy Compounds" that had been designed by the BNCR Locomotive Engineer Bowman Malcolm. The first Class A locomotive had been built by the BNCR at York Road, Belfast in 1901 shortly before amalgamation with the Midland Railway and building continued with the Midland Railway constructing six at their Derby works. The locomotives were built as two-cylinder compounds using the Worsdell-von Borries system, the high pressure cylinders having a diameter of 18 inches (457 mm) and low pressure ones of 26 inches (660 mm), both with 24 inches (610 mm) stroke.

Following the end of World War I the state of the locomotives operating in Northern Ireland was well below that which was needed to run the services effectively; many needed replacing but, however, cost was a major factor. It was decided to implement a "Renewal Programme" in which, not only would new locomotives be built but also suitable classes of locomotives would be rebuilt, in the main following the style of the Midland Railway and the LMS.

As part of this "Renewal Programme" members of Class A were rebuilt as two-cylinder simples (i.e. not compounds). Those reclassified as Class A1 were rebuilt with a Midland Railway type RG6 boiler and new cylinders both of 18 inches (457 mm) diameter by 24 inches (610 mm) stroke. The boiler was higher pitched than the original to allow the firebox and ash pan to clear the rear driving wheel axle and an extension of 24.75 inches (630 mm) to the smokebox saddle was needed to offer support. Although the effect was less striking than that of the similarly rebuilt Class B3, the modified appearance was such that these locomotives would be included among those that gained the nickname of "Whippet" because of a perceived resemblance to the racing dog.

All the class were officially named after mountains although that allocated to No. 58, Lurigethan, was never carried.

The majority of the Class A1 engines were coupled to what was known as the "Standard" tender which could carry 6 long tons (6.1 t) of coal and 2,090 imperial gallons (9,500 l; 2,510 US gal) of water. No.34, however, ran with one of the three "Medium" tenders that had a 2,590 imperial gallons (11,800 l; 3,110 US gal) water capacity and No.62 acquired a spare built up tender with a capacity of 2,690 imperial gallons (12,200 l; 3,230 US gal). No.58 acquired a tender cab which led to her being a regular visitor on the Dungiven branch where tender first running was required.

Nos.33, 58 and 69 later received boilers with a working pressure of 200 psi (1.38 MPa) in place of 160 psi (1.10 MPa). This led to their being allocated to the Belfast area during the late 1930s where duties were more onerous. No.33 was shedded at York Road while the other two were at Larne.

No.65 worked in a spare capacity at York Road and No.62 was based at Cookstown.

The builders plates showing dates in the late 1920s and early 1930s belied the age of these engines and the heavy traffic that they handled during World War II showed up their weaknesses more than newly built locomotives. Nevertheless, the majority of the class survived to be taken into Ulster Transport Authority stock and were scrapped in the mid 1950s.

• Arnold, R.M. (1973). NCC Saga. Newton Abbot: David & Charles. ISBN 0 7153 5644 5.
• Arnold, R.M. (1973). Supplement to NCC Saga. Whitehead: Railway Preservation Society of Ireland.
• London Midland and Scottish Railway (Northern Counties Committee). Class A1 general arrangement drawing. Belfast: LMS (NCC).