Cockney feet mark the beat of history, sang Noël Coward, as if he had ever been east of Holborn. Yet the sugary wartime sentiment finds a moving and resonant echo in Melanie McGrath’s new work of social excavation. The past casts an unusually deep shadow over Bow. And, cleverly, she has found a fresh means of exploring these striated layers of heritage: through the enduring local appetite for minced beef pie, mashed potatoes, and side orders of stewed eels.