Sigh I guess you are being deliberately obtuse you are the one who put an inadequate reference in place with no page numbers and no indication that the information you insist on adding is actually included in the references you want to use a single definite reference which actually supplies the relevant information for the definite statement Unlike most British engines Merlins and Kestrels were usually right hand tractor is infinitely better than a whole screed of references which may or may not say the same thing I have the Jane s AWA aircraft 1945 1946 although several British engines listed supply the direction of rotation not all entries do so eg Armstrong Siddeley Cheetah XV Bristol Centaurus Hercules Pegasus Mercury so it isn t quite as clear cut as you like to make out as your list above also shows