Can anyone advise me on this Elizabeth shilling

I am confused:-
mm is clearly ‘1’ (obv & rev)
no rose or date
diam is 30-31mm (weight 5.1g)
ear is showing
‘ET’ vice ‘Z’ in obv inscription
All in all, does not match any Sp. Nearest, I believe, is Sixth Issue (SP#2577) but mm is wrong. Could it be ‘Mule’?
Any comments would be most gratefully received
Kevin
