GB KEVII, ½d Blue-Green, SG216, PERFIN Dublin Corp. ( 3 Castles) Dublin Postmark for Nov 9 1902

"Three Castles in Shield" PERFIN used by Dublin Corporation.  

This was in use from 1897 to 1907, thereafter the shield was removed as the stamps tended to separate along the shield holes instead of the proper perforations.

With 157 perfin holes, this is one of the most heavily 'perfinned' stamps