Well it's a Cartwheel Penny from your measurements but if you could attach a photo, that would help us value it plus there's two varieties so we don't know which one you have. The £2 Bill of Rights also had two designs made, one for Scotland and one for England. We would need a picture for that too however the Englsih variety is worth £4 in uncirculated condition, which yours probably won't be, whilst the Scottish one is worth £8 in uncirculated condition. Pictures please!