Hi JoMe and Mathias,
Thank you for the additional information. I am not sure about Martin Becker as he had 58 victories, but the tail only shows 43. Of course it could be that he stopped using that aircraft and the markings were no longer updated, but I guess they would have overpainted the old markings.
Could it be Herbert Lütje's aircraft? He was Gruppenkommandeur of IV./NJG 6 until October 1944. By that time he had 42 victories (source:
https://www.luftwaffe.cz/lutje.html)
But Lütje had one victory over a B-17 at daytime. The markings on the tail look all to have British roundels and a diagonal black line (= victory at night?). I am not sure if all of Becker's victories were at night and over British aircraft.
Regards,
Roger