In good condition, a bespoke (not official) variation of the British Royal Naval 1845P Cutlass.
This cutlass has been period made especially; there is old pitting / rust around / under the tang nut (this is not a recent marriage). It has an 1845P cavalry blade, a 1796P cavalry stirrup hilt, and an 1845P naval cutlass grip. Possibly a merchant navy officer’s weapon as there are absolutely no markings. Though there are some old nicks to the cutting edge, so this could have been a marine infantry / artillery officer’s sword during the Crimean War. If you like unusual / rare cutlasses, this one is for you!
The very long 35 inch blade is in good condition but has several old nicks to its cutting edge. The entire cutlass is a little loose now (these things are literally simply held tight by the tang nut), but is generally very good.
They do not get much rarer than this. Yours for £400. Please quote item reference AD19. Full sized / additional photos available upon request. Box 0428-1.18 (1.954).