6.—(1) Subject to regulations 7, 8(8) and 19, an authority shall hold a referendum by virtue of this Part where it receives a valid petition (but shall not be required to hold such a referendum where it receives a petition which is not a valid petition).
(2) A petition may be presented to a local authority—
(a)by properly addressing, pre-paying and posting it to the authority’s principal office; or
(b)by delivering it to the authority’s principal office.