5SAn order under section 1(3) of the M1 Trunk Roads Act 1936 (power to provide that a road superseding part of a trunk road should itself become a trunk road) continued in force by the proviso to section 12(3) of the M2 Trunk Roads Act 1946 and section 14(7) of the M3 Special Roads Act 1949, and still in force (whether or not varied under those provisions) immediately before the commencement of this Act, shall continue in force and may be varied or revoked by a subsequent order made in the like manner subject to the like provisions