Crossed Keys hallmark - Help Needed

[jackk]

Here is a silver basket with a glass insert. Hallmarked on the bottom with crossed keys and WB for the maker. Similar hallmarks can be seen for Liegnitz (Legnica), Posen (Poznan) and few other cities. I assume this is of German origin. Any help.

[Theoderich]

there are some towns with crossing keys

Buxtehude, Lauban, Liegnitz, Minden, Posen, Regensburg, Riga, Xanten,Uerdingen, Neuveville

I think it is not Lauban, Posen, Regensburg,Xanten,Uerdingen, Neuveville

I think it could be Minden

BZ: could be Scheffler, Goldschmiede Rheinland-Westfalens #863 (ca.1830)
there was a (No17a) Friedrich Wilhelm Beerbaum OO1819 +1825
there is no makersmark in the Schefflerbook

but I am not sure