What is the test for a vendor who failed to deliver a copy of a contract?

I take this section to mean that while the purchaser is not bound merely by signing such a contract, but may revoke liability at any time until it is signed and a copy of it delivered by the vendor, he may nevertheless waive his right to revoke, as in this case, by accepting the implement and making part-payment of the purchase-price. On the other hand there can be no doubt that the vendor having delivered the implement pursuant to this contract signed by the purchaser and having accepted part payment of the purchase-money, is bound by the terms of the contract as effectually as if he had signed it and made due delivery of a copy of it to the purchaser. This failure of the respondent to sign and deliver the contract is the sole ground upon which its validity is attacked, and as the objection cannot prevail, the only point left undetermined is whether or not the contract was in fact executed by the appellant. If it was, the Act is satisfied and the contract is valid, and the judgment entered in favour of the respondent must stand. If it was not so executed there is no valid contract, and the parties are in the same position as is found to exist in the case of Sumner v. Squires, ante, p. 98, in which I wrote a judgment today. I think, therefore, that the case should be referred back to the learned trial Judge who heard and saw the witnesses, in order that he may determine the question of fact which is still undetermined.