What is the consequence of a mortgagee’s failure to pay interest on a mortgage?

In Smith v. Smith Romer J. said, at p. 552: “It seems to be a settled rule of practice that, after default has been made by a mortgagor in payment of the principal and interest in accordance with the proviso for redemption contained in the mortgage deed, he must either give the mortgagee six calendar months’ notice of his intention to pay off the mortgage, or must pay the mortgagee six months’ interest in lieu of notice. This is the well-settled general rule. But no doubt the rule is subject to some exceptions.”