21.—(1) Subject to the provisions of this Act, where goods are sold by a person who is not the owner thereof, and who does not sell them under the authority or with the consent of the owner, the buyer acquires no better title to the goods than the seller had, unless the owner of the goods is by his conduct precluded from denying the seller’s authority to sell.

(2) Provided also that nothing in this Act shall affect—

(a) The provisions of the Factors Acts, or any enactment enabling the apparent owner of goods to dispose of them as if he were the true owner thereof;

(b) The validity of any contract of sale under any special common law or statutory power of sale or under the order of a court of competent jurisdiction.