If you’re looking to redevelop or renovate, having a property that’s a listed building can be both a help and a hindrance. The crucial factor is knowing exactly where you stand before you start.

Leading estate agency Knight Frank offer some words of advice.

Listed buildings are designated by the Secretary of State for Culture, Media and Sport, with advice from English Heritage, as being of "special architectural or historic interest".

The purpose is "simply to put a mark against certain buildings to ensure that their special interest is taken fully into account in decisions affecting their future".

The main criteria:

* Architectural interest: All buildings which are nationally important for the interest of their architectural design, decoration and craftsmanship; also important examples of particular building types and techniques.

* Historic interest: This includes buildings which illustrate important aspects of the nation’s history.

* Close historical association with nationally important buildings or events.

* Group value, especially where buildings comprise an important architectural or historic unity or are a fine example of planning (such as squares).

The older and rarer a building, the more likely it is to be listed. The vast majority of those built before 1700 which survive in anything like original condition are listed, as are most built between 1700 and 1840.

After that date, the criteria become tighter because of the increased number of buildings erected and the larger numbers which have survived, so that post-1945 buildings have to be exceptionally important to be listed. To date there are about 500,000 individual buildings, in England, estimated to be protected.

Listed buildings are graded:

* Grade I buildings (about 8,000) are those of exceptional interest

* Grade II* (about 26,000) are particularly important buildings of more than special interest.

* Grade II are of special interest, warranting every effort to preserve them. There are about 465,000 buildings.

Grants for repairs of listed buildings are available from English Heritage and local authorities. With the VAT zero-rating of improvements made as a result of listed building consent, it means that period charm has a better chance of surviving the 21st century.

(Source: Department of Culture, Media & Sport)