I have an old 54 BN-1 gathering dust, in the shop, Smith Gas gauge #49422/219, black face, similar gauge, Smith's manual part # FG 2530/19 is same gauge,may have different face, in MG-A, Mk 1 Midget, early MG-B, Triumph TR-2, 3,
Hemmings Motor News has instrument restorer that can duplicate your face.
Water & oil, looks typical too, Smith's Face #X42638/38
regards. Jean-Pierre Fontana