CA 15 April 1987. Appeal by estate agents (W) from decision dismissing W`s claim to commission on the sale of a house. The vendor (V) instructed two agents, W and Beauchamp Estates Ltd (B), to find a purchaser. The point at issue was which agents was the effective cause of the sale. The purchaser negotiated with the vendor through both agents simultaneously, without telling either the agents or the vendor. In a separate action heard at the same time it was held that B were entitled to commission on the sale. B had made the first contact with the purchaser in August 1982. In September 1982 W showed the purchaser the property which he said he had not seen and an offer was made which was not acceptable to V. In November 1982 the purchaser was shown the property again by B and an offer was made which was accepted. CA held it was not a case where two commissions were payable as V did not know that the bids were coming from the same source.