This coin is a very recent find and was unearthed by Oliver Jackson. I was asked for my opinion on what it might be worth.
The coin is a gold sovereign of George V. I’ve seen lots of gold sovereigns as detecting finds but I have never managed to locate one.
Oliver’s find is dated 1915 on the reverse. There is a very small letter M close to the hoof of the horse resting on the ground line. Therefore, this sovereign was struck at the mint situated in Melbourne, Australia. During the reign of George V, besides London, sovereigns were struck at a number of overseas mints, which include Bombay, Ottawa, Perth, Sydney and Pretoria. Some of these can be of considerable rarlity and sell for very high prices.
This 1915 Melbourne mint sovereign isn’t a rarity but neither is it one of the very common issues. It would grade at least VF and no defects show up in the images I received. However, the gold does look a bit pale, which is probably the result of being in the soil for close to one hundred years. As it stands, the present market value would be close to £340.