6. Registration of fencing covenants to expire after 12 years---(1)
 Where a fencing covenant is registered under the Land Transfer Act 1952
 after the commencement of this Act, or where a covenant, agreement, or
 proviso (being a fencing covenant within the meaning of this Act) was
 registered under the Land Transfer Act 1952 before the commencement of
 this Act by virtue of section 7 of the Fencing Act 1908, the
 registration of the covenant, agreement, or proviso shall expire after
 the expiration of 12 years from the date of the registration or the date
 of the commencement of this Act, whichever is the later.

   (2) Nothing in subsection (1) of this section applies in respect of a
 fencing covenant that protects a local authority from liability to
 contribute towards any work on a fence between a public reserve vested
 in or administered by that local authority and any adjoining land.