Not a daft question at all. Australian sovs (full and half) are identified with an M or an S or a P (Melbourne, Sydney and Perth). They are pretty small and may be worn down on the older coins. Roughly speaking (as there are variations) these single letters sit above the date on the ones with the dragon and may be at the top or the bottom of the older ones with the shield. A good light and a magnifying glass helps with the older coins. If the mint mark is SA then they are South African and no mint mark means they are from the UK. Hope this helps.