Apoligies H..correction London mint. It was pretty late when i replied
Half asleep lol. You can compare the IM stars here on this site and probably tie it down. I can't decide if its 3a1 or 3ab1. I am not seeing a pellet around Rex or III so maybe 3ab1 but it's not always present on 3a1 coins.
https://www.rodblunt.com/long-cross-pennies-class3-ct