During the period form 1971 to 1982 Great Britian moved from their old monetary system of farthings, pence, shillings, guineas, sovereigns and the like to a new decimal system. The new system is not as romantic, but probably more functional. In the new system, there are 5 new pence in one shilling, 25 new pence in one crown, and 100 new pence in one pound.
Wayner has a 25 new pence crown.
These coins were issued in normal 'business' strike as well as collector 'proof' strike. The business strikes are copper-nickel and the proof strikes are 0.925 silver. The coin in our picture is a proof strike which has mirror-like surfaces. So mirror-like are the surfaces, you can see the camera in the picture.
Business strikes are worth face value. Proofs are worth their weight in silver. A 25P crown contains 0.841 troy ounces of silver. Use kitco.com to get the current price of silver, then multiply by 0.841.