Before decimalisation, 6d used to buy me 6 chocolate marshmallow teacakes from the school tuck shop at 1d each. Then 6d became 2 1/2p and 1d became 1/2p. Thus I could only buy 5 teacakes. What a rotten swizz!
So 2p would have bought you 4 teacakes.
You'd have to check with a bank or post office re. using your coin, Molly. However, if it's a 'pewtery' colour then it doesn't sound like 2p to me. Unless we're at crossed purposes on the definition of pewter. It's a sort of dull, silvery colour, right?