The intricate pattern of distribution of the Devon breeds of sheep can be broadly related to variations in natural conditions. Some ebb and flow in the popularity of breeds is to be expected as a result of changing economic circumstances. Pre-war, there was wide scale crossing with the Dorset Down and South Down rams to obtain earlier maturity. Since the war, the ploughing-out and the new marketing arrangements for fat-stock have brought a revival of interest in the pure-breeds, but as in other parts of Britain, the change over to dairying, especially in West and Mid-Devon, has been accompanied by a permanent reduction in sheep flocks.