The church interior is beautifully furnished and lovingly maintained. A feature is the large number, more than forty, stained glass windows and doors - a priceless heritage.

Throughout its history St Peter's has undergone almost continual development. It has been built, demolished, rebuilt, altered, upgraded and extended according to the needs of the time. Always, however, the changes have been in harmony with the original. Building stone for extensions, though said to have been from different quarries, is, to the untrained eye, almost indistinguishable from the original.

Interior furnishings, including the glorious pipe organ, have been similarly refurbished, added to and upgraded almost continuously. Gas lighting of the 1850's gave way to electric lighting, heating was installed, pulpit and choir stalls added, carpet laid, amplification system installed. A tapestry group turned every plain kneeler in the church into an exquisite work of art. A children's play area was added, and cupboards installed so that morning tea could be enjoyed at the back of the church after services.

The most recent alteration was in June 2005 when the wrought iron rood screen was relocated to the back wall of St Michael’s Chapel where its fine work can be seen in detail against the white wall. The relocation of the screen was to enable the chancel to be extended to accommodate a nave altar. A fine cedar altar was beautifully crafted to compliment the design of the church and the existing furnishings.

St Peter's has always been fortunate in having highly skilled engineers and architects etc among its parishioners. Their work has helped make the various extensions and alterations possible. And of course, gifts from parishioners over the years have decorated the church in tasteful and beautiful ways.

St Peter's Church has been registered by the National trust of South Australia as a building of great heritage and value. The parish celebrated one hundred and fifty years of worship in St Peter's Church 2002.