Municipality of Neu Wulmstorf (Harburg county / Lower Saxony).
Its ratio is 3:5. It's a blue over yellow horizontal bicolour with
the coat of arms in the centre of the flag.
Description of coat of arms: The shield is divided per chevron but
the chevron is touching the upper edge. The chief (both rests) is golden
(=yellow), the base is
blue with a silver (=white) annulet at the bottom.
Source: I spotted the coat of arms on 29 March 2007 at municipalities
boundary. The image of flag matches the description given in http://kommunalflaggen.de/.
The flag was submitted on 2 September 1965 at Hauptstaatsarchiv
Hannover. The image matches also the description as given in Hauptsatzung
§2 (2), the municipal constitution, dated 9 November 2000 published
in "Amtsblatt 47/2000 vom 30.11.2000" p.860.
Klaus-Michael Schneider, 8 Apr 2007