This is an ornate kind of harware that was massed produced in the late Victorian period. Probably between 1880 and 1900. If you want to see many examples, go on eBay and look at "Eastlake Hardware" or "Victorian Hardware" and you will see all sorts of different exampples and styles.
These samples of hardware dont strike me as particularly Eastlake, or Anglo-Japanese or (fill in) but they kind of look like the common, scroll-ey cast iron patterns throughouty late victorian homes in the US
Digging around the internet, I found these very similar reproduction latches:
Very similar, but not exact duplicates...
If you are interested in exactly what this is, I think that you should email the picture to Bill Rigby or Ed Donaldson. I have spent a lot of time studying and buying antique hardware for my house. Among people with an internet presence, the above people are clearly the most knowledgeable about actual antique hardware. Bill Rigby used to be active on this site (www.wmjrigby.com) and Ed Donaldson (www.eddonaldson.com) is not a member of this site, but he has a site that suggests a greater level of knowledge than most internet sites that do not have clear descriptions of hardware. Rigby specializes in new old stock and Donaldson specializes in restored stock. Both can probably name the maker in their sleep.
THANKS!! I'll do that...