The Belfast and Northern Counties Railway (BNCR) Class A was a class of 13 two-cylinder compound steam locomotives built for service in north-east Ireland. The first two members of the class would be the last locomotives to be built for the independent BNCR, being completed before its purchase by the Midland Railway in 1903. The members of the class were rebuilt by the LMS (NCC) becoming either Class A1 or Class U2 depending on how they had been modified.

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The BNCR had standardised on locomotives with a 2-4-0 wheel arrangement for its passenger locomotives during the 1870s and construction continued through to the mid-1890s. However, with increasing loads and heavier trains the limitations of this wheel arrangement became apparent. The first purpose-built 4-4-0s, the Class B "Light Compounds", had been in introduced in 1897 but something more powerful was needed to supplement the two Class D "Heavy Compounds" that were rebuilt to 4-4-0s at the same time.

The Class A locomotives were designed by the BNCR Locomotive Engineer Bowman Malcolm and were the last design of broad gauge locomotives to be built for the independent Belfast and Northern Counties Railway, the first two being completed before its purchase by the Midland Railway in 1903.

The first Class A Engine was No.34 which was outshopped from York Road in April 1901 and named Queen Alexandra. The second of the class, which had the distinction of being the last locomotive to be built by the BNCR, was No.3, King Edward VII, which was completed fifteen months later in July 1902. Building continued over a seven-year period after the take-over of the company by the Midland Railway. Six locomotives were constructed at the Midland Railway's Derby Works and the remainder at York Road works.

The locomotives were built as two-cylinder compounds using the Worsdell-von Borries system, having an 18-inch (457 mm) high-pressure cylinder and a 26-inch (660 mm) diameter low-pressure cylinder, each with 24-inch (610 mm) stroke. Inside Walschaerts valve gear was fitted which was standard on the BNCR. The driving wheels were of 6 ft (1.829 m) diameter. The only visible difference between the two builders was the number of spokes on the bogie wheels, the Belfast-built batch had nine spokes while those built at Derby had ten.

Two main, and visibly obvious, changes were made to the locomotives when in traffic, viz: the fitting of Manson automatic tablet exchange apparatus for working single lines, and a rearwards projecting extension of the cab roof, offering more protection for the crew.

The Class A engines were coupled to what was known as the "Standard" tender which could carry 6 long tons (6.1 t; 6.7 short tons) of coal and 2,090 imperial gallons (9,500 L; 2,510 US gal) of water.

Five members of the class were renumbered between 1924 and 1927 when Nos. 3, 4, 5, 9 and 17 became Nos. 33, 62, 59, 69 and 58 respectively.

The BNCR painted the locomotives "invisible green" (a very dark bronze green that looked almost black) with vermilion, light blue and yellow lining. The initials "BNCR" in block capitals were carried on the tender sides.

The livery remained the same under Midland Railway administration with the addition of the diamond shaped Midland Railway crest to the cab sides and the initials "NCC" in gold block capitals on the tender sides. Buffer beams were vermilion, and the smoke box was black.

• 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 A general arrangement drawing. Belfast: LMS (NCC).