One particular British coin ... Numerous other coins command hundreds and even thousands at auction. Take, for example, a 1983 2p coin that was accidentally struck with 'New Pence' on the reverse ...

and the 2s6d or 2/6 coin was “half a crown,” the crown being the unit of currency in Scandinavia. There was no crown coin except for commemorative issues. The slang word for the sixpence was ...