Conzen: The southern end of the Percy Terrace ribbon already includes in embryonic form a distinct type of accretionary growth which is very different from the arterial ribbons or from fringe-belt units (Fig. 15a). At the southern end of the Easter Piece a rather deeper parcel of land was available for building, capable of containing more plots of comparable size than could be accommodated on its existing road frontage. It was therefore developed as a single new plan-unit for the accommodation of ten houses and their plots, mostly in small terraces. The required additional road access was provided by South Street, a short cul- de-sac opening up the interior of the whole parcel and functioning solely as a minor residential street with no traffic other than that to adjoining plots. Such a purposeful arrangement or design of buildings, plots, and associated new roads opening up back land is fundamentally different from a ribbon that develops spontaneously along an already existing road without unified design. It constitutes a layout in the technical sense of the town-planner and ushers in the long sequence of residential layouts which have increasingly dominated modern accretions. The South Street layout was small enough to remain entirely orientated on Percy Terrace and looks almost like a part of that ribbon. Yet morphologically it is far more independent than Belvedere Terrace, for example (Fig. 15h)