Locomotive test report, British Railways (London Midland Region), Performance and efficiency, Class 5, 2-6-0 No 42725 (Walschaerts valve gear), Class 5, 2-6-0 No 42824 (Poppet Valves), To compare otherwise identical locomotives fitted with two types of valve and valve gear, Special technical features list Poppet valves operated by Reidinger rotary gear, January 1957. 7.874 x 12.5984 in. (NRM Technical Archive reference TEST/LMS/14)