[Jim McDougall]

Interesting smallsword Efrahjalt, and nicely done tentative research, thank you for sharing those details with us and for posting this.

Samuel Harvey and his sons of Birmingham were key in the advance of British swordmaking in the mid 18th century, but they were engaged in the production of munitions grade military swords. While later Birmingham makers such as Gill, Osborne and Wooley did produce swords in accord with the military patterns beginning in unofficially in 1788, they were never producers of smallswords as far as I am aware.

The production of smallswords was typically by cutlers in London and several other locations, many of these cutlers were also jewellers (check Southwick).
The hilt was likely quite likely gilt, and cutlers typically used hall marks on such hilts (again Southwick).

The H4 was probably administrative stock number or of that sort.

I am pleased to see you do not tamper with patination, which in my opinion should be left as is (my historian position) and cleaning, especially overcleaning which compromises the integrity of the piece (again my opinion).

I think this very well may be a commemorative sword celebrating the victory at Waterloo, which was a practice in Great Britain post Napoleonic campaigns. I once had M1803 infantry officers lionhead, which instead of the flowing mane, had one with a sphinx like headdress.

Here I would note that the eagle from the standard of the French 45th Regt. captured by Sgt. Ewart of Royal Scots Greys at Waterloo would have been an unsurprising theme on a sword for a British officer. The blade has similar etched motif to British officers swords, and the hilt form is of court sword style of the period.

"London Silver Hilted Swords", Leslie Southwick, 2001