3.—(1) Section 6 of the Act shall apply to the specified proportion of any specified work if it is proposed to be carried out—
(a)on or after 1st October 1997 by a local authority which is subject to, or created by, a structural change or substantial boundary change effected by an order made under section 17 of the Local Government Act 1992(1) “a structural change”) where that structural change takes effect from 1st April 1995;
(b)on or after 1st October 1999 by a local authority which is subject to, or created by, a structural change where that structural change takes effect from 1st April 1996; or
(c)on or after 1st October 1998 by a local authority which is subject to, or created by, a structural change where that structural change takes effect from 1st April 1997; or
(d)on or after 1st April 1998 by county councils or non-metropolitan district councils which are not subject to a structural change; or
(e)on or after 1st October 1996 by any other defined authority except
(i)those mentioned in section 1(1)(b), 1(1)(c), 1(1)(d), 1(1)(f) and 1(1)(g) of the Act; and
(ii)a police authority.