According Krackers list:
http://www.aircrewremembrancesociety...anPilotsG.html
PILOT NAME: Gresens, Walter
RANK: Oblt
SCORE: 2
UNIT(S): 1/ZG-76 (12/39), Stfkpt 11/NJG-1 (10/41)
AIRCRAFT TYPE(S): Bf 110
HONOURS: EK 2, Night Fighter Operational Clasp
OPERATIONAL DETAILS: Most likely the same person as Oblt Gresens in JG-1, like Paul Förster. One known victory, a Wellington 25 km northwest of Borkum, 18 December, 1939. A 2nd Wellington P-2520 of RAF No. 9 Sq., on 12 April, 1940 (Rosseels).