If you bought your property through the Right to Buy scheme you are likely to have had a discount. The council secures this discount as a registered charge against the property for five years.
If, within these first five years, you want your mortgage lender to release equity from your property for improvements or other reasons, in a similar way your mortgage lender will need to secure the release as a registered charge. The mortgage lender will insist on the charge taking priority over the council's charge.
In order to do this your lender will need to make an application for a 'deed of postponement'. If approved, the council will register its charge as a third charge and allow your lender to place a second charge (the first is placed by your lender to secure the original sum of the mortgage).
The council will only approve a deed of postponement for improvement works to your property or if you are changing mortgage lenders.