I concur that it's not an athame.
Athames in the Wiccan sense post-date Gerald Gardner and WWII (although in theory, there should be some older ones somewhere). Additionally, they are more likely to have black handles and various magical symbols on them. The blades are also likely to be one or two edged, not cruciform.
As the others have pointed out, the English have had a long fascination with various pagan symbols, so finding a dragon or green man in the decorations isn't a sign of a pagan tool.
Best,
F
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