I believe that is CN, not silver. Hard to tell from photo if you have the Proof or Prooflike. Value $20-25
I have this commemorative crown. made of Cu-Ni and you can get it for below Krause catalog value over the internet. doesn't diminish its appeal though. looks a little prooflike to me, but it might just be me, not having too many proofs to admire yet
It is definitely one of the nicest circulating base metal coins in pre-decimal Britain, and the reverse has once again been revived, but this time in silver, with the new "crown" for the birth of Prince George of Cambridge.
if i'm not wrong, these commemorative crowns are being accepted as 5 pound coins after they were re-evaluated for their size? seems strange to me that such a huge heavy coin would be worth only 25p, since 5 shillings make 60 pence. then again 60 pence made a 1/4 of a pound....
I have one of these also. http://www.cointalk.org/threads/festival-of-britain-crown-1951.75285 They originally came in a box with a certificate.