Mortgagee right to sell

[Simeon79]

If a property has been mortgaged for its full value, what right does the mortgagee have to sell the property if they wish to do so? Obviously they can issue possession proceedings if repayments on the mortgage are not being made and, from there, sell the property as the Mortgagee in Possession. Are there any circumstances under which they can otherwise sell the property? Could someone simply make them an offer on the property if they wanted to buy it?