While most stores at Heathrow Airport, including World Duty Free, still technically accept cash, they strongly recommend and prioritize card or contactless payments. In 2026, many retailers have moved toward a "cash-light" model to speed up transactions. If you do wish to pay in cash, you can generally use Great British Pounds (GBP), Euros (EUR), and US Dollars (USD), though change is almost always given in GBP. It is important to note that if you use the "Reserve & Collect" service—where you order items online to pick up at the airport—you must pay at the collection point, where cards are the standard and swiftest method. Some smaller kiosks or "unmanned" grab-and-go shops at Heathrow may be strictly card-only. If you have a large amount of foreign currency you want to get rid of, World Duty Free is usually the best place to use it, but it is always wise to have a backup debit or credit card (like Visa or Mastercard) as some individual registers may not be equipped to handle cash.