Another Swedish piece with a strange mark:

A dessert knife, 8 1/4" (21cm) in length, with a King's pattern handle.

As can be seen, it bears Stockholm marks for 1842. The mystery mark is overstamping the maker's mark, part of which can be seen at the top.
Is there enough of the maker's mark visable to make an identification?
Does anyone recognise the mystery mark? Perhaps an official Government department. With such a large mark, a huge amount of force would have to be applied to make such a perfect impression, most likely with the use of a fly-press.
Any help appreciated.
Trev.