F1If an order is made under Part IV of the M1Local Government Act 1972 constituting any area as a new county or altering the area of a county, a combination scheme may be made under this Act with respect to that area before that date but so as to come into operation on or after that date; and in relation to such a scheme the provisions of this Act shall apply subject to any necessary modifications and as if for references to the fire authority there were substituted references to the fire authority for any county, . . . F2 or combined area of which the whole or any part is to be comprised in F1the new or altered county.