According to Gilkerson the cast iron handle with 18 ribs and 6 vertical grooves first appeared on the Brit 1804 cutlass. The handle was almost straight.
Later versions of the handle are more shaped with a swelling and slight curve at the end to fit in the hand better. The 1830's coastguard cutlass is an example.
And this one - courtesy of Cap'n Mark.
http://www.vikingsword.com/vb/showthread.php?t=12145
The straight handle on yours would tend to indicate nearer the early part of the century.
The 1814 appears with both types of handle. But for a cutlass that did not go into production there are an awful lot of examples. I believe most of these were private purchase using blades similar to those shown in the catalogues (see above post) some of which were marked with GR.
Which, I think, is why you sometimes see what appears to be an 1814 blade with a hilt that is much less than the double disk.
regards, CC.