In 2001 the Royal Mint issued a commemorative £2 coin to commemorate the wireless being installed across the Atlantic Ocean. It was struck for circulation, for VIP collectors in Proof Sterling Silver and for VVIP collectors in Silver Proof Piedfort. That is double the normal thickness in Sterling Silver.
These come in a protective capsule but with no case or certificate. Some collectors prefer them this way so they can put the capsule straight into their cabinet so this may well be just right for you at a much better price!