Half-plan at church-floor level drawn by Edward Strong. Drawn scale at base of sheet, fractionally over 5 ft to 1 inch (10 ft = 50 mm), with inch divisions at the left end. At top left, a separate, slightly inaccurate scale, just over 5 ft to 1 inch (10 ft = 48.5 mm).
The walling in the crypt is not quite as executed, for the recess at the end of the aisle was built straight-sided rather than splayed from early 1677 and the long window recess in the portico wall was made narrower on its inner side (6.5 ft rather than 9 ft; the recess was narrowed and re-positioned on the drawing in pencil but not as finally built). The plan at this level probably dates shortly before the Building Committee ordered a start on the foundations of the 'North & South Porticoes & Cross Isles' [transpets] in November 1676. The plan at church-floor level is, by contrast, very nearly as built from 1678-84 and is drawn and annotated in a darker ink than the crypt-level plan.
The handwriting and annotations compare closely with those on Edward Strong's construction drawing for the upper apse of 1685-86, especially in the writing of the '8's and '4's and the use of chevrons, dashes and fractions. In 1681 Strong took over his elder brother Thomas's areas of construction on the latter's death. These areas included the west half of the north transept where the team had worked from late 1676.
The architrave of the 10-ft door opening is further out in relation to the engaged column and the framing pilaster strip is wider. The door surround was built in 1683-84 to the dimensions marked on the plan but the frame was set back by about 3 inches related to the column. This change could have been made shortly before construction of the surround. The built design is first recorded in a quarter-plan of the crossing and transept of c.1685.
A wall passage sketched in broken pencil outlines near the opening has the word 'pasage' in handwriting similar to Strong's. The passage is incomplete but is shown widening above the end walls. It was redesigned in 1685-86 when screen walls were added above the end walls.
Square holes near the south-east angle and the inner angle of the window splay mark the drainage holes ('water holes' in the accounts) that were built close to these positions.