Where a mortgagee’s power of sale in regard to land has become exercisable but does not extend to the purposes mentioned in this section, the court may, on his application, authorise him and the persons deriving title under him to dispose—
of the land, with an exception or reservation of all or any mines and minerals, and with or without rights and powers of or incidental to the working, getting or carrying away of minerals; or
of all or any mines and minerals, with or without the said rights or powers separately from the land;
and thenceforth the powers so conferred shall have effect as if the same were contained in the mortgage.
The county court has jurisdiction under this section where the amount owing in respect of the mortgage or charge at the commencement of the proceedings does not exceed £30,000.