Sounds very interesting, do you know if there are any other recorded examples of your mule? I saw an incredable mule sovereign on Ebay.com in BU. It was the observe of 1826 and a reverse of 1823, it was STUNNING.
That is a 1916 Penny in 'Fine' condition and is worth no more than £1. However, the coin is in very good condition for it's age considering it would have been in circulation until 1971.