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Shortly after the Canadian engines were built, Captain Howey bought for them two American locomotive chime whistles. Sir Nigel Gresley, Chief Mechanical Engineer of the L.N.E.R., liked the sound of the first one, fitted to No. 9, so much that Captain Howey presented him with the whistle destined for No. 10. Sir Nigel put this whistle on his new 2-8-2 locomotive Cock o' the North and had similar whistles made for the " A4 " Class Pacifies which followed. He later presented Captain Howey with a chromium-plated " A4 " whistle and in 1953 this was put on R.H. & D. No. 10, which still carries it.
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From World's Smallest Public Railway by P. Ransome-Wallis 4th edition 1964