Local Authorities in Great Britain have had the power to acquire, declare and manage LNRs since 1949 under Section 21 of the National Parks and Access to the Countryside Act. A Local Authority can include a County Council, District or Borough Council and/or a Parish Council. The responsibility for selecting, acquiring and managing LNRs lies with the local authority, although the government's advisory body on nature conservation in England, i.e. English Nature, needs to be consulted by the local authority in their use of the powers given to them under the 1949 Act. English Nature do stress however, that they themselves have no mandatory powers in the decision-making process, and that the consultation is purely advisory. The only guidelines that exist for the selection of LNRs are contained within the 1949 Act. This states that LNRs must afford special opportunities for study and research on wildlife or natural features and must preserve flora, fauna or geological features of special interest in the area.

The LNR designation provides a focus for a local community and opens opportunities for education, as well as offering a useful tool for managing and protecting areas of open green space.

In defining the purpose of a nature reserve, the Act does not provide any strict definition of what is "special", nor does it attempt to define "in the area". English Nature's own guide to LNR selection and designation states that they look to the judgement of the local authorities in defining sites of special importance to nature conservation. English Nature also advises that "in the area" means the area over which the authority has responsibility and that evaluating sites for study and research needs to be done only in the context of the area over the local authority have a remit.

The perceived role and purpose of LNRs in contributing to nature conservation has changed since the 1949 Act. From their own perspective, English Nature considers LNRs to have an important part to play in the conservation of biodiversity. However, they recognise that "local authorities may be more interested in the contribution LNRs make to the quality of the environment for local people, the part they play in community development and their value in education".

Community Strategies and the Biodiversity Action Plan have reinforced the importance of LNRs to the local community. LNRs have an important part to play in the Community Strategies and Local Biodiversity Action Plans, where the designation not only has benefits for wildlife and education, but there is huge potential for community involvement.

Scientific evidence suggests that there are also physical and psychological benefits of access on a regular basis to natural greenspace and local authorities are encouraged to provide a minimum of 1 hectare of LNR per thousand population.

Over recent years, all of these factors have increased local authorities commitment to declaring sites as LNRs. In addition, English Nature has increased its support and encouragement to local authorities to make a more positive use of their powers to provide LNRs.