What is the test for novation in a mortgage?

In Mead at p. 427 Wilson J. outlines the requirements for a novation: A novation is a trilateral agreement by which an existing contract is extinguished and a new contract brought into being in its place. Indeed, for an agreement to effect a valid novation the appropriate consideration is the discharge of the original debt in return for a promise to perform some obligation. The assent of the beneficiary (the creditor or mortgagee) of those obligations to the discharge and substitution is crucial. This is because the effect of novation is that the creditor may no longer look to the original party if the obligations under the substituted contract are not subsequently met as promised. Because assent is the crux of novation it is obvious that novation may not be forced upon an unwilling creditor and, in the absence of express agreement, the court should be loath to find novation unless the circumstances are really compelling. Thus, while the court may look at the surrounding circumstances, including the conduct of the parties, in order to determine whether a novation has occurred, the burden of establishing novation is not easily met. The courts have established a three-part test for determining if novation has occurred. It is set out in Polson v. Wulffsohn (1890), 2 B.C.R. 39 as follows: 1. The new debtor must assume the complete liability; 2. The creditor must accept the new debtor as principal debtor and not merely as an agent or guarantor; and 3. The creditor must accept the new contract in full satisfaction and substitution for the old contract. and at p. 430: In my view, significant changes in the terms of a mortgage effected without the consent of the original mortgagor constitute very strong evidence of novation. It is not necessary, of course, for a different contract to be brought into existence for a novation to take place. The essence of novation is the substitution of debtors. However, where significant changes in terms occur and the creditor has not applied to the original mortgagor for its consent, I believe this is a strong indication that the creditor is no longer looking to the mortgagor for payment.