England is obliged by UK law to maintain lists of species and habitats of principal importance for biodiversity conservation; the other countries within the UK: Wales, Scotland and Northern Ireland, have their own laws for this purpose. Public bodies, including local authorities now have a legal duty to have regard to conserving biodiversity in the exercise of their normal functions.^[1] In England, this obligation derives from the Natural Environment and Rural Communities (NERC) Act 2006.^[2][3]

The species that have been designated to be of "principal importance for the purpose of conserving biodiversity" are those that are most threatened, in greatest decline, or where the UK holds a significant proportion of the world's total population. They mainly derive from lists originally drawn up for the UK Biodiversity Action Plan (UK BAP). Similarly the list of habitats of principal importance in England also derive from the UK Biodiversity Action Plan. Both lists were reviewed in 2007, and the total number of UK BAP habitats increased from 45 to 65, and the number of UK BAP species increased from under 600 to 1,150.^[4]

From these, the formal list just for England (and laid out below) finally contained 56 of those 65 habitats, and 943 of the original 1,150 UK species.^{[5][6][7][8][9]}

The latest update to the list of Section 41 habitats of principal importance (priority habitats) was published by Natural England in August 2010.^[13][14]

The list shows the broad habitat group, followed by name of the habitat of principal importance (as used by original source).

The latest update to the Section 41 list of species of principal importance for the conservation of biodiversity in England (priority species) was published by Natural England in May 2014. It now includes 943 species.^[15]