London’s many plague pits have a certain dark allure – they’re mysterious because so many of them lie unmarked, hidden and forgotten under the city’s streets, buildings and parks. We’ve seen pictures of archaeologists excavating long-lost mass graves uncovered on building sites, with huge jumbles of bones emerging from the soil and centuries-old eye sockets peering out at us. We’ve heard dark tales of homes built over old plague pits, haunted by restless spirits. But upstream of the old city, in a quiet suburb by the Thames, a plague pit lies in plain sight – marked by a yew tree and a little memorial. This is the plague pit at All Saints church, Isleworth, where local plague victims were laid to rest in a mass grave in 1665.