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Sir Arthur Percival Heywood, of Duffield Bank, Derbyshire (1849-1916), 3rd Baronet, eldest son of Sir Thomas Percival Heywood. 
1874-1916 Built six miniature locomotives to a 15 inch gauge. The boilers were built by Abbott and Co of Newark.
A thorough and detailed account of Sir Arthur Heywood's railway engineering activities was published in 1995 . The following information is extracted from that book.
Sir Benjamin Heywood, the first holder of the Heywood Baronetcy, was a wealthy banker. The Baronetcy passed to Thomas Percival Heywood (b.1823 at Acresfield). His eldest son was Arthur Percival Heywood, born at Doveleys near Uttoxeter on Christmas Day 1849.
From an early age APH was interested in lathework, having watched his father use his Holtzapffel lathe (bought from the estate of Sir H. Fleetwood). His interest in things mechanical continued, but social constraints ruled against a career in engineering.
In 1871 Heywood graduated in Applied Science at Trinity College, Cambridge.
He married his cousin, Margaret Effie Sumner, in 1872. His father bought the couple a house and grounds at Duffield Bank near Derby. Here he built a workshop and railway, and undertook extensive experiments with 15-inch gauge railways, ostensibly with a view to establishing that gauge for commercial and military use. The railway became known as the Duffield Bank Railway.
A workshop was built, with a well-equipped machine shop, forge, erecting shop, iron foundry, brass foundry, carriage shop, pattern shop, saw mill. These were powered by a Crossley gas engine. In the yard was a 5 ton hand crane made by R. C. Gibbins.
Heywood completed his first locomotive, EFFIE, in 1875. It was an 0-4-0 well tank.
The second locomotive, the 0-6-0 tank engine ELLA, was more interesting, particularly in regard to the articulation system and the valve gear. A description was given in The Engineer 1881/07/15.
The next engine was MURIEL, an 0-8-0T, completed in 1894. Again this had a flexible wheelbase. On one occasion it hauled a train of eight bogie vehicles with 124 passengers around a loop of 40 ft radius with a gradient of 1 in 47. Heywood copied the design of split enclosed coupling rod brasses from Samuel Geoghegan.
Heywood built a railway system, including the locomotives KATIE (0-4-0T, SHELAGH (0-6-0T) and URSULA (0-6-0T) for the Duke of Westminster's Eaton Hall Railway.
Heywood built 9-inch and a 15-inch gauge railway systems - the Dove Bank Railway - at his other home, Doveleys.
Following the building of ELLA until 1915, Heywood's Engineer at Duffield Bank was William Midgeley.
Following the outbreak of WW1, activity at Duffield Bank wound down, and some of the Heywood's locomotives and rolling stock were bought for use on the Ravenglass and Eskdale Railway.
Sir Arthur Heywood died during a visit to Duffield Bank on 19th April 1916.
An auction sale of the railway stock followed Heywood's death. ELLA and MURIEL were requisitioned by the Ministry of Supply, and were subsequently bought for the Ravenglass and Eskdale Railway. However, the steam-raising ability was inadequate for the hard labour on the railway, due to restricted firebox capacity. KATIE went briefly to Ravenglass, before going to Llewelyn's Miniature Railway at Southport, and thence to Fairbourne.