Hi welcome to the forum.
The ‘Norwegian flag’ and other little mark, I believe is the mark of : Plus workshop or the Applied Arts Center & school of Fredrikstad Norway. Known for its modernist designs often hammered. RH could be the initials of the designer.The mark has been punched a second time hence misalignment.
See for another well known silver smith, who worked for Plus workshop and makers'mark example:
http://www.925-1000.com/no_vigeland.htmlAnd a little more information about Plus:
http://effie-graa.com/egc/library/artists/info_ECH.htmYou have been forgiven the tarnish but please give it a little LTC
Oel.