Where under section 1 of the [1955 c. 20. (4 & 5 Eliz. 2.).] Agriculture (Improvement of Roads) Act 1955 (proposals for effecting improvements in certain roads situated in, or affording access to, livestock rearing areas), a county council submit proposals to the Minister of Agriculture, Fisheries and Food for effecting an improvement to which that Act applies in respect of a highway that is not a highway maintainable at the public expense, and that Minister approves those proposals, then, without prejudice to any other enactment (whether contained in this Act or not) whereby the highway may become such a highway, the council submitting the proposals shall have power, by notice exhibited on or near the highway, to declare it to be for the purposes of this Act a highway maintainable at the public expense, and thereupon—
(a)the highway shall become such a highway, and
(b)if, apart from this section, any person would be liable to maintain the highway under a special enactment or by reason of tenure, enclosure or prescription, that liability shall be extinguished.