In fitting out the church after the Great Fire, the parish decided to place the communion table on a marble ascent, with steps and a chequered marble floor for the chancel. It also commissioned new altar rails of Sussex wrought iron, with large panels of scroll work and repoussé ornament, which date either from 1683 or from the subsequent refurbishment of the church in 1705/6. The sides formerly returned against the east wall but were moved forward to make the sanctuary larger as part of the restoration of the church in 1924.
St Magnus had been a pioneer in London in installing communion rails as early as the 1570s. The rail around the altar was removed in 1641 but restored in 1663, one of the churchwardens recording that:
At the east end thereof ascending up four large stone steps standeth the Communion Table New and fayrely Rayled round about with weynscott raylles with benches and seats round the raylles.
However, the arrangement of the sanctuary in the post-Fire church was a matter of some contention:
The Vestry in May 1678 voted to remove the new ascent to the communion table, which was ‘to be set in the body of the church or chancel according to the rubric of the Church of England’. Having earmarked some funds and appointed some workmen to level the chancel, the vestry then prudently added the caveat ‘so far as it may be lawfully done’. In the event, Wren or the bishop must have intervened, and it appears that table and step remained undisturbed.
‘According to Ancient Custom’: The Return of Altars in the Restoration Church of England: Kenneth Fincham