Where a notice to quit part of an agricultural holding is given to a tenant, being a notice which is rendered valid by section 29 of this Act, and the tenant within 28 days after—
(a)the giving of the notice, or
(b)where the operation of the notice depends on any proceedings under the foregoing provisions of this Act, the time when it is determined that the notice has effect,
whichever is later, gives to the landlord a counter-notice in writing that he accepts the notice as a notice to quit the entire holding, to take effect at the same time as the original notice, the notice to quit shall have effect accordingly.