The exact use and date of the knife is still unknown. I have
been lucky enough to speak about this object to many people with
experience of historic objects, and although no-one has known for
certain yet, there have been several fascinating theories! Some
have suggested a 17th century date for it. The shape of the blade
and the octagonal handle could support this, but it remains
speculation for the moment.
As for the purpose, some have suggested it might be a tool for
weighing mail, with the knife possibly serving as a letter opener.
But the spring is very stiff, which suggests to me that it was
intended to weigh something quite heavy, and indeed the markings on
the brass rod measure in increments of 380 grams so it is much too
stiff to weigh individual letters. Yet the knife's blade is quite
modest in size, so it seems unlikely someone working with heavier
materials, such a butcher or fishmonger, would have had much use
for it! Also, the presence of the gold seems to suggest it had a
decorative or ceremonial purpose as well as a practical one. I have
jokingly suggested it might be a special 'ceremonial'
cheesemonger's knife, though even for cutting cheese the blade is
likely too small!
Hopefully someone out there will have an answer, but until then
it has been a real pleasure to work on such an unusual, endlessly