I think the only silver pennies (and Fourpence and Twopence) issued during George VI's reign were maundy issues. Mintage for Maundy money is always pretty low, there's some mintage figures and indicative values (for the sets) here, but I don't know how up-to-date this is: http://www.maundymon...6064/14115.html According to this the mintage for the 1938 set was 1,275 pieces. BTW the coin will be 50% silver, not sterling (92.5%), as maundy money was debased along with the rest of our coinage in 1921, though was restored back to sterling silver in 1947 when silver was removed completely from our circulating coinage . Hope this helps! Sorry, I've just read your post again, you've said it has Britannia on the reverse (which the maundy penny doesn't) - I don't know of any British silver penny of 1938 with Britannia on it - sounds more like a 19th century groat! Is it British or a colonial coin? Or it could be a Penny that someone has had dipped in silver. Silver would weigh more if genuine, get it weighed and let us know.