The best family hotels in London share a particular intelligence: they understand that children have different priorities to parents, and that the best family hotel experience serves both simultaneously rather than forcing a compromise. This means connecting rooms or family suites with genuinely useful floor space (not a single room with a fold-out cot in the corner), hotels within walking distance of the activities on the family itinerary, breakfast that children will actually eat, and staff who engage with children as people rather than accessories.
Geographically, the most family-friendly London hotel zones are South Kensington (within walking distance of the Victoria and Albert Museum, the Natural History Museum, and the Science Museum — London's three greatest free museums for children), Covent Garden (excellent theatre, close to the London Eye and the South Bank), and the area around Hyde Park (the Diana Memorial Playground, the Serpentine paddling pool, and the park's 350 acres of free space).
Connecting rooms are significantly rarer in London than in American or Asian luxury hotels — the Georgian and Victorian buildings that house most of London's quality accommodation were not built with family travel in mind. The best family properties tend to be either purpose-built modern hotels (citizenM, Montague on the Gardens) or converted townhouses with naturally larger room configurations. Always specify 'family room' or 'interconnecting rooms' explicitly at booking, and confirm again before arrival.
For practical London family travel, the Oyster/contactless tap-in system allows under-11s to travel free on all TfT services when accompanied by a paying adult — a significant saving when a family of four is travelling by tube. The double-decker bus network is slower than the tube but offers a child-eye-view of the city that no underground journey can replicate, and many of London's best routes pass key sights.