How old is the drainage under a typical Fitzroy terrace?
Often as old as the house. Fitzroy was largely built between the 1850s and 1880s, and a meaningful proportion of its original drainage is still in service, sometimes with sections replaced piecemeal over the decades. That means you can have early earthenware, brick, mid-century clay and modern PVC all in one run. A CCTV inspection is the only reliable way to know what is actually under your property and what condition each section is in.