Royal UK Mint did not produce sovereigns in 1875. Only Sydney and Melbourne did, and out of those, only Sidney produced any with the Shield Back design (though they also produced St. George with the Dragon reverses that year too). This is a lovely average circulation example for your viewing pleasure.
Well, after recalibrating my scale today I made the discovery that my sovereign weighs 7.95 grams. The British Empire cheated me out of 0.03 grams of gold. Darn it. That's one thing I've noticed about a lot of old gold coins, including US. The older you get (specially anything pre-1920s), expect a tiny variance in weight on a fair portion from what it should be on paper and what it actually is, even on some AU or BU coins. I'd complain to Queen Victoria about her mints needing better scales in 1875, but I'm 147 years too late for that. Plus for the last 121 years I doubt Victoria has much cared for anything at all (at least when it comes to earthly matters).