Since its completion in 1669 the building has undergone numerous alterations, including:
Roof
Wren’s original roof was replaced with the present roof in 1802 by George Saunders.
The present cupola, replacing Wren’s earlier smaller version, was designed by Edward Blore in 1838.
More recently, in 2007, the slated roofs, (covered with green Westmoreland slates), were overhauled, in advance of the reinstatement of the ceiling paintings.
Windows
Wren’s original windows were replaced with timber sash windows in 1767-68. During the major restoration works 1958-63 new oak windows were installed being similar (but not identical) in design to Wren’s originals.
External stonework
Various parts of the external elevations have been re-faced over the years - with repairs known to have been carried out in 1826, 1838 and 1911. During the 1958-63 restoration project, further extensive repairs were carried out to the stonework, including the complete re-facing of all elevations and the re-building of the parapets and balustrading at roof level.
Marble statues
In 1737 statues of Archbishop Sheldon and the Duke of Ormonde (carved in white marble by Henry Cheere) were installed in the niches on the South Front elevation. A statue of King Charles II, also carved by Henry Cheere, was placed in the niche over the north doors. All of the statues were however removed during the major restoration works 1958-63 due to their poor condition.
"Caesars' Heads"
The original stone heads to the north (Broad Street) boundary wall were replaced in 1868. The current stone heads were carved by local stone carver Michael Black and date from 1972.
Internally
In 1935-37, the timber structure supporting the galleries around the auditorium was found to be in poor condition and a steel frame was inserted to provide suitable support. Further improvements were also carried out at that time, including the introduction of electric lighting. In 1962-63 the original timber floor of the auditorium was replaced with a new reinforced concrete "coffered" floor.
Organ
At the opening ceremony on July 9 1669, a temporary organ was used. The first organ was built in 1671 by 'Father' Smith. Bernhard Schmidt (1629-1708) was a German organ builder who settled in England in 1660. He later built an organ in St Paul's cathedral. This organ was replaced in 1720 by a new organ built by Renatus Harris (c.1652-1724), one of Father Smith's rivals. Harris was from a family of organ builders which had temporarily fled to France (where he was born) when music in church was forbidden by the Puritans and the organ building trade was in recession.
In 1733 George Frederic Handel (1685-1759), conducted a performance in the Theatre of his Oratorio Athalia which he had written especially for Encaenia of that year.
Harris's organ was replaced in 1858 by one built by Henry 'Father' Willis, (1821-1901). (The name of 'Father' had been bestowed on Smith to distinguish him from other younger members of his family who worked with him and it was in tribute to his contribution that two hundred years later the same nickname was bestowed upon Willis whose circumstances were in this respect very similar.)
The current organ case was designed by Sir Thomas Jackson in 1876. It was later extended, to fill all but two of the windows on the South Gallery, before being reduced to its present size in 1961-63.
In 1998 the present digital organ, the gift of Robert Venables QC, was installed by J. Wood & Sons Ltd.
