After the commencement of this Act, a prior mortgagee shall have a right to make further advances to rank in priority to subsequent mortgages (whether legal or equitable)—
if an arrangement has been made to that effect with the subsequent mortgagees; or
if he had no notice of such subsequent mortgages at the time when the further advance was made by him; or
whether or not he had such notice as aforesaid, where the mortgage imposes an obligation on him to make such further advances.
This subsection applies whether or not the prior mortgage was made expressly for securing further advances.
Save in regard to the making of further advances as aforesaid, the right to tack is hereby abolished:
This section applies to mortgages of land made before or after the commencement of this Act, but not to charges on registered land .