19. Fence erected when occupier of adjoining land exempt from
 liability therefor---(1) Where at the time when any fence was erected
 the occupier of the land on one side thereof had, by reason of section 3
 of this Act or of the Fencing Act 1908 or any corresponding former Act,
 no liability to contribute to the cost of the erection, if the occupier
 for the time being of that land has thereafter become liable to
 contribute to the cost of work on that fence---
   (a) The person who erected the fence, or his successor in title, may
         serve upon the occupier of that land a notice in writing
         requiring him to pay an appropriate share of the value of the
         fence at the time when the notice is served taking into account
         any contributions made towards the cost of the erection and
         maintenance of that fence by any occupier of that land; and
   (b) That occupier shall, within one month after receiving the notice,
         pay that share to the person who erected the fence, or to his
         successor in title, and so long thereafter as he continues to be
         the occupier shall be liable to bear half the cost of work on
         the fence.

   (2) This section shall not apply in any case where the exemption from
 liability to contribute to the cost of the erection of a fence arose by
 reason of a fencing covenant or any other covenant, agreement, or
 proviso relating to fencing.
     Cf. 1908, No. 61, s. 19