It's a very rare coin by modern standards. If you've seen one go for £2700, then that's what one person was prepared to pay for one. The only thing against it is that it's a decimal coin, and - 20p mule aside - is the only well known decimal rarity, in a market that's dominated by over-priced Royal Mint issues and slashed-price secondary market decimals. I don't see Charles coming to the throne will make any difference to its value, and whether you keep hold of it depends entirely on your needs and wants. If you're a coin collector, £2,700 would buy you some very nice 20th Century items, or a smaller number of pre-20thC coins. I know what I'd do!  Yeah, I'd sell it in a heartbeat, although I think £2,700 is unrealistic.....but you never know. £2,700 would buy a nice 1869 penny, when one becomes available.  You can buy my 1869 for a lot less than that....