The NBR 141 Class consisted of two steam 2-4-0 locomotives built by the North British Railway (NBR) in 1869. They were the direct antecedents of the NBR 224 Class 4-4-0.^[2]

Thomas Wheatley became locomotive superintendent of the North British Railway (NBR) at the start of February 1867.^[4] During his tenure of seven years, he provided the NBR with 185 new locomotives;^[4] but only eight of these were suitable for hauling express passenger trains, the first two of which were these 2-4-0s, nos. 141 and 164, which were built in 1869;^[5] the remaining six were the 4-4-0s of the 224 and 420 Classes, introduced in 1871 and 1873 respectively.^[6]

Originally the 141 Class had leading wheels of 4 feet 0 inches (1.22 m) diameter, coupled wheels of 6 feet 6 inches (1.98 m) diameter, and cylinders measuring 16 by 24 inches (406 by 610 mm). The boilers were domeless, with the safety-valves mounted above the firebox. The frames were single, the driving wheel splashers had eight slots; there was no cab, but a weatherboard with two circular windows. The six-wheel tender held 1,650 imperial gallons (7,500 L) of water. They were very good locomotives, and when the cylinder diameter was increased by 1 inch (25 mm), the performance was not adversely affected.^[4][2]

On the NBR, locomotives were generally rebuilt when their boilers wore out.^[7] Matthew Holmes, locomotive superintendent of the NBR between 1882 and 1903, rebuilt both locomotives in 1890; amongst the improvements were a domed boiler, Westinghouse brake and a cab.^[5][1] In later years, no. 141 was used on trains between Glasgow and Dundee.^[5]

Every six months, the NBR renumbered some of its older locomotives into a "duplicate list", in order to vacate numbers for new construction.^[8] Accordingly, in 1912, nos. 141 and 164 were placed on the duplicate list, becoming nos. 1158/60 respectively. They were both withdrawn from service in 1915 and scrapped in 1923.^[5][2]

The locomotives may have been named after 1875 – it has been stated that Drummond, who replaced Wheatley in 1875, named NBR engines "including those already in service".^[9]

• Baxter, Bertram (2012). Baxter, David; Mitchell, Peter (eds.). British Locomotive Catalogue 1825-1923, volume 6: Great Eastern Railway; North British Railway; Great North of Scotland Railway; Midland & Great Northern Joint Railway; Remaining Companies in the LNER Group. Southampton: Kestrel Railway Books. ISBN 978-1-905505-26-5.
• Boddy, M.G.; Fry, E.V.; Hennigan, W.; Proud, P.; Yeadon, W.B. (July 1963). Fry, E.V. (ed.). Locomotives of the L.N.E.R., part 1: Preliminary Survey. Potters Bar: RCTS.
• Boddy, M.G.; Brown, W.A.; Fry, E.V.; Hennigan, W.; Manners, F.; Neve, E.; Tee, D.F.; Yeadon, W.B. (April 1968). Fry, E.V. (ed.). Locomotives of the L.N.E.R., part 4: Tender Engines - Classes D25 to E7. Kenilworth: RCTS. ISBN 0-901115-01-0.
• Haresnape, Brian; Rowledge, Peter (October 1982). Drummond Locomotives: A Pictorial History. Shepperton: Ian Allan. ISBN 0-7110-1206-7. DX/1082.
• Highet, Campbell (1970). Scottish Locomotive History 1831-1923. London: George Allen & Unwin. ISBN 0-04-625004-2.
• Locomotives of the North British Railway 1846-1882. Stephenson Locomotive Society. 1970.