A rear extension to a house in a Highgate conservation area for which consent was obtained after over a year of protracted negotiations with the planning authority. A combination of a controlled range of natural materials and a palette of understated colours integrates the new work with the old and the interior with the garden and the newly formed terraces. The key materials used are Brazilian slate flooring, western red cedar for the decking and fence panels, American oak doors, windows and purpose-madedining table, Zodiaq crushed limestone kitchen worktops, and self-rusting exterior steel cladding panels. A powder-coated aluminium guttering system with invisible clips feeds rainwater from the natural slate roof to a robust steel drainage chain rusted to the same colour as the adjacent steel panels. A sliding fully glazed door 2.9 metres in length retracts into the panelled wall to open the entire flank of the new dining room out to the lower terrace.