The main aim of conservation is the preservation of our cultural heritage for future generations. Today, conservation is generally defined as the ‘management of change'. This definition recognises that all buildings and artworks change over time, whether by means of natural physical change, such as the building-up of a patina, or by deliberate action, such as additions, repair or damage. In many cases in the past, conservators attempted to recreate the original state, often by means of removing significant historical accretions. Today, such alterations are often recognised as being valuable in their own right and as evidence of the object's past history and usage.

Modern conservation does not inhibit appropriate change or prevent access. Rather, it attempts to reconcile the needs of the object or building with the needs of the people who use or visit it. For churches, this means that a careful balance has to be struck between the needs of the congregation, worship and mission on the one hand and, on the other, the requirements for the long-term preservation of the building or the object.

Churches are unusual among historic buildings in that so many are still used for their original purpose after a history of up to a thousand years or more. Naturally, during their history many changes have occurred and as the needs of the congregation change the building has to be adapted accordingly. But all decisions about change have to be fully informed and mindful of the building's significance.