I have had problems sourcing new belts for wartime Bedford, Austin and Humber especially as the angle of vee and width do not equate to the British Standard A, B, C, etc. There was apparantly, at the time a BS Automotive standard which is no longer recognised. A compromise has to be made and it usually means having to find a belt that rides a little higher in order to get grip on the flanks. Sometimes it is worth looking around autojumbles, if you have a list of numbers from various makers, ie John Bull, Ferodo, etc.