It would help if you posted a better head-on pic of the throat showing the hole under the horn, and a better shot directly from the side, showing a cleaner profile of the hanging end. Another thing you can do is lay it on its side and coat it with oil and look at it from a low angle - the shininess can help you see very faint depressions that are hard to see otherwise. Hard to say what it is. I agree that the pattern and the shape and layout of the number stamps do look like a Mousehole, as well as the numbers being stamped instead of raised, but one issue I see is that there do not appear to be any dots between the numbers. Mousehole anvils nearly always have dots, or bullets, between the numbers, and the dots are usually quite deep, to the degree that the dots are sometimes the only visible marks left. Possibly Mousehole, but I would think it is more likely a minor brand and possibly the work of someone who learned anvil making at Mousehole and struck out on their own. It would be pretty heavy for a Wilkinson, most are considerably smaller, in the 150 lbs range. It would also be exceedingly rare for a Wilkinson to display the stone weight, almost all are noted in actual pounds, and I have only heard of 1 exception. If it is a Wilkinson, the makers mark would usually be on the other side, so look carefully for a mark that looks like a pair of crossed hot dogs. Other than that, I don't know what t tell you - There are a lot of little known brands.