8SThe mean of the average prices so calculated shall be subject to adjustment by the valuer within the limits of 30 per cent upward or downwards as he may think proper having regard to the general condition of the stock under valuation and to the profit which the purchaser may reasonably expect it to earn. The resultant figure shall be the basis of the valuation of the ewes and is in this Part of this Schedule referred to as the “basic ewe value”.