Drawn by Edward Pearce, and complementing the elevation, this incomplete half-plan explores the setting out of the portico, steps and front retaining wall. Drawn scale, 4 ft to 1 inch (10 ft = 62.5 mm).
Pearce's hand is apparent from the double-ruled scale bar with rightward-slating numbering and the parallel pen shading on the columns. He probably drew this plan and the accompanying elevation soon after he began work master mason on the south side of the cathedral in early September 1678. The transept door opening is 9 ft wide and in most respects matches the design in Wren's early elevation of the transept portico. The relationship of the portico to the upper flight of steps is the same as in Wren's elevation save that a 10th step has been added to the lower flight. The aisle is at its built dimension of 19 ft internally.
The drawing bears inscriptions in pencil by the unidentified draughtsman which gave the dimensions of the portico at the level of the steps and the bases of the columns. The radius from the centre of circle, at half the depth of the transept wall, to the centres of the columns is 21 ft.