Very early Mk1 Minis were subtley, but visibly, different in the front. The front valance is referred to as "Full Skirt", and does not have the cutouts in the corners. This one, for 1963 and 1964 Cooper has the lip turned down for mounting the oil cooler, the diagonal brace to the slam panel, and proper Mk1 number plate brackets.
Use this on any 1964 and earlier with oil cooler mounted behind the grille.