As of March 2026, London is effectively a cashless city. You can spend an entire week in the capital without ever touching a physical banknote. All public transport (The Tube, buses, and trains) requires contactless payment (via credit/debit card, Apple Pay, or Google Pay) or an Oyster card; they literally do not accept cash. Almost every street performer, "Big Issue" seller, and market stall in places like Borough Market or Camden now uses portable card readers. The only very rare exceptions where you might want a small amount of cash (e.g., £20) are for leaving tips for hotel housekeeping, small independent "mom-and-pop" shops in rural areas outside London, or if a specific digital system goes down. For the modern tourist, a travel-friendly credit card with no foreign transaction fees is infinitely more useful than a wallet full of pounds. In fact, some trendy cafes and bars in Shoreditch and Soho have now gone "card only," making cash a burden rather than an asset.