Thanks for the brilliant close-up and the other details. That's got to be one of the clearest photos of hallmarks I've ever seen, you can see every atom, and you are quite right, marked for Hukin & Heath, Birmingham assay office, 1898-99.
As you may know this well known Birmingham firm were highly regarded for their claret jugs and decanters. They were also elevated from the ordinary by the great English Victorian designer, Christopher Dresser, but your piece, with its emphatic Art Nouveau shape, is a little after the era when he designed for Hukin & Heath.
This triple handle, triple spout form would have been used as a port decanter. It was traditional in English upper class society for the men to drink port at the end of dinner in the evening, the ladies having first withdrawn to the drawing room (literally the "withdrawing room" which is how it got its name). The port was always decanted and always passed to the left (probably an old Royal Navy custom, as it would be un-seamanlike to pass port to starboard, as it were). This three-handle, three-spout construction was a clever way of allowing the port to be passed hand-to-hand and with a spout opposite each new holder.
Originally it would have had an elaborate blown glass stopper, perhaps something like this:
As for value, the most desirable Hukin & Heath port and claret jugs are the whimsical animal and bird forms, but this one would be quite sought after too, despite its lack of stopper.
If you were to sell at a good antique auction house or on line (eBay, Amazon, etc) it would fetch in the range of $150 - $225. It therefore has a full retail or replacement value of $450 and is what you should insure it for.
I do hope this helps!
PS. If there's anything more I can help you with on this, please don't hesitate to ask. If not, could you very kindly rate my services (with the stars or "accept" button) as this is how I get paid by JustAnswer at no extra cost to you. We can still continue to communicate here on this thread after you do. And if you have another item you'd like to ask me about, just start a new Question and put "For Robert S....." in the subject line. Thanks, R.