(1) This section applies despite anything to the contrary in any Crown grant or instrument of trust.
(2) The trustees of library land may lease it or a part of it to any person, if the land to be leased is not immediately required for library purposes.
(3) A lease under this section—
(a) if it is a building lease that provides for the erection of buildings for library purposes and associated purposes, must be for a term of not more than 50 years; and
(b) in any other case, must be for a term of not more than 31 years; and
(c) may be on any other terms that the trustees think fit.
(4) The trustees must not apply rent received under a lease under this section for any purpose except—
(a) repaying money borrowed under this Part or a corresponding previous enactment and paying interest in respect of any money so borrowed; or
(b) a library purpose or an associated purpose being a purpose authorised by the document creating the trust or any relevant document of title.