A Napoleonic Period British Navy Silver Mounted Officer's Dirk Hallmarked for the year 1808

An attractive and fully hallmarked for the year 1808 silver mounted British naval officer's dirk with ivory handle. The maker's initials are 'MY'. Each of the three silver mounts are hallmarked either fully or partially which is rather rare. The 10 1/2" blade has a very slight curve at the tip. The overall length is 14 1/2". This appears to be a real 'fighting' dirk rather than a purely dress or ceremonial dirk. The silver lion mask guard is the only example I have seen.