So any "silver looking" coin pre-1947 will contain silver - 3d, 6pence, shilling, half crown, crown, florin etc... anything pre-1920(i believe) is 92.5% silver.

Ive had a garrett ace 250 metal detector for about 8yrs. Ive found several little coins in my time, no coins of any value mind. I dod once find a medievil gold finger ring, that had to be declared as treasure. Its now aat in the cardiff natural history museum in a darkcdraw never to see the light of day again.