Protecting London’s ecological backbone 

London may be considered as one of the world’s largest urban sprawls, but it is also home to a remarkable network of habitats. From ancient woodlands and wetlands to grasslands, chalk streams and wildflower meadows, the UK’s capital is home to an abundance and diversity of wildlife, much like its human inhabitants, offering ample opportunities to bring people closer to nature. 

Many of London’s most well-loved green and blue spaces are recognised as Sites of Importance for Nature Conservation, otherwise known as ‘SINCs’. Unlike other national and international designations, such as Sites of Special Scientific Interest (SSSIs) or Ramsar sites, SINCs don’t have statutory legal protection. They are, however, protected within the planning system when designated in London Boroughs’ Local Plans (the planning framework that guides future development, infrastructure, and land use within their areas). SINCs are highlighted in the London Plan (2021), which Local Plans have to follow. Furthermore, the significance of SINCs in London’s green infrastructure is demonstrated through initiatives such as the Rewild London Fund, which committed more than £2.48m over three years to support projects that enhance and restore SINCs across the city¹. 

As of March 2026, London is home to 1,749 SINCs, ranging from small community-managed spaces to landscape-scale reserves. They are present on both private and public land, and as a network provide vital habitat links, protect rare species, buffer sensitive habitats from surrounding land use change, and contribute to health and wellbeing by offering spaces of oasis and escape from bustling city life.

SINCs and their history in London 

The SINC system has a long and influential history. First established in London in 1985, SINCs played a leading role in recognising and protecting locally significant sites for wildlife. The SINC system opened the doors to the recognition and protection of important habitats that didn’t meet national thresholds but are still vital within their local landscape. 

This London-born approach helped shape what is now known across the UK as the ‘Local Wildlife Sites’ network. Today, Local Wildlife Sites exist throughout the country, although, despite Defra’s advice to unify their naming, regional individuality persists and their name still varies across the UK (see table 1).  

Local Planning Authorities typically identify these sites following robust, scientifically determined criteria. Wildlife Trusts nationally have historically played key roles in supporting local and regional planning authorities to establish systems for identifying, monitoring and managing Wildlife Sites relevant to local contexts, building on Defra’s nationally reaching guidance². 

Examples of regional terminology for ‘Local Wildlife Sites’ 

Reviewing London’s SINC criteria 

Between 2024 and 2026, London Wildlife Trust worked in partnership with the Greater London Authority (GLA) and Greenspace Information for Greater London CIC (GiGL), London’s Environmental Records Centre,  to review and update London’s existing SINC selection criteria to ensure it remains robust, transparent, and reflective of London’s current ecological and planning context. 

The review included a series of consultations and workshops with London Boroughs, environmental NGOs, Friends of Parks group networks and a scrutiny panel of regional experts. This collaborative approach helped to ensure that the updated criteria reflected both scientific evidence and the practical experiences of those working on the ground to protect nature across London. 

The revised SINC criteria are now published on the GLA website as the new SINC advice note. 

View the SINC Advice Note (see ‘Related Documents’)

Reaching practitioners and communities 

Alongside the criteria review, the project developed a set of resources to help improve understanding of SINCs and how they fit within the London planning system. These resources aim to support a wide range of audiences, from local authorities, ecologists, community groups, developers, consultants, and interested members of the public. 

Spaces Wild

Spaces Wild, originally published in 2015, is a tool for championing the various roles that SINCs play, both for nature and for people. It includes a series of case studies from across London’s diverse Boroughs, to show practical examples of how SINCs have been managed, created, enhanced, and how they support both London’s wildlife and residents. It also highlights key papers and policies relating to SINC protection and recognition, both locally and nationally.  

Read Spaces Wild 2^nd edition (2026) 

The SINC Resource Hub 

GiGL has developed and now hosts the SINC Resource Hub. “The Hub” brings together key information, guidance and resources related to SINCs in one place. The Hub will continually evolve as new information and resources are added. 

View the SINC Resource Hub - GiGL

A special thank you to Land Use Consultants, Mott Macdonald, and all London Boroughs and SINC scrutiny panel members who contributed to the development of the SINC resources. 

References  

¹ Greater London Authority (2023) Rewild London Fund 2023. Available at: Rewild London Fund 2023 | London City Hall 

² Department for Environment, Food and Rural Affairs (DEFRA) (2006) Local Sites: Guidance on their Identification, Selection and Management. Available at: Local Wildlife Sites DEFRA guidance PDF  

Read more about SINCs and the Rewild London Fund on our blog post here