I flew XN557 a lot in '61. It was a CFS aircraft, but I can't recall any difference from the Mk 3s I flew at Syerston in '60.
XN557 colour scheme was: Tip tanks - dayglo. Wing outer panel, not ailerons, from the centerline of the roundel outward, top and bottom - dayglo. Ailerons, top and bottom - silver. Flaps, top and bottom - dayglo. Inner wing - silver (with black walk strip on root top). Rear fuselage, aft of point where fin merged with fuselage, but not including any fin or the tailcone - dayglo.Remainder of fuselage, not nosecone -silver. Nosecone, swept back and under to a point between the air intakes- dayglo. Tail - silver. Tailcone - metal. Don't forget the black anti-glare on the nose.
Dick