The flag design is based an illustration in an article by Ottfried Neubecker in Die Fahnen und Standarten der Armee des Koenigreichs Hannover, which was published in several parts in the Zeitschrift für Heereskunde (Berlin) in 1934, A flag of this form, according to Neubecker, was carried by at least some of the field battalions, although it is unclear whether they were actually carried before 1816.
Neubecker also doesn't specify any of the colours on the flag, so what I have presented here is an educated guess based on other Hanoverian flags and heraldry.
The figure is a Der Kriegspieler British line or guard infantry regimental colour bearer from the set # 150: British Line/Guard Infantry 1815, Command Group.
The first task was to rub off the original British regimental colour markings using a steel burnishing tool from a ceramic arts set. I then inscribed the roundels using another steel ceramic arts tool. The roundels are a little larger than they ought to be as I wanted to give myself a little space to work with and to help fill up the huge expanse of white on the rest of the flag.
One of the interesting things about this figure is that it is not based on the Hinton Hunt British infantry officers, but on the British Royal Artillery officer instead. Whoever made him evidently forgot to remove his sword hilt from his left hip!
I could have used British light infantry officers for this battalion, but went for the line infantry variants as it seems fairly clear that the Bremen battalion's officers wore Belgic shakos. There's a very good illustration of one (albeit in his original light infantry green) in the Anne S. K. Brown Military Collection, here.
The rest of the battalion is past the halfway mark and should be ready to put on show by next weekend.
Wir sehen uns dann!