Found this
CFDs allow investors to profit on the movement of a share price without actually owning the physical stock. Similar to other derivative instruments such as futures contracts, two parties enter into an agreement to settle at the close of their contract the difference between the opening and closing price of a companyâs share price.
Firms that offer CFDs are able to hedge their exposure to the contracts by physically buying the underlying stock, and by doing so enjoy a tax concession that means they do not have to pay stamp duty.
CFDs have rapidly grown in popularity in recent years, and this has been reflected in government revenues from stamp duty, which have traditionally been one of the largest contributors to the Treasuryâs coffers.
I thought someone somewhere did not pay!