The National Health Service (NHS) Executive for London carried out an investigation in 2002 as part of their wider mental health strategy to establish whether existing mental health advocacy provision in the city was meeting need. The project took a two-part approach, with an emphasis on, (a) mapping the provision of advocacy services and, (b) cartographic mapping of service location and catchments. Data were collected through a detailed questionnaire with service providers in collaboration with the Greater London Mental Health Advocacy Network (GLMHAN) and additional health and government sources. The service mapping identified some key statistics on funding, caseloads and models of service provision with an additional emphasis on coverage, capacity, and funding stability. The questionnaire was augmented by interviews and focus groups with commissioners, service providers and service users and identified differing perspectives and problems, which informed the different perspectives of each of these groups. The cartographic mapping exercise demonstrated a spatially—even provision of mental health advocacy services across the city with each borough being served by at least one local service as well as by London wide specialist schemes. However, at local level, no one borough had the full range of specialist provision to match local demographic need. Ultimately the research assisted the Advisory Group in providing commissioning agencies with clear information on the current status of city-wide mental health advocacy services, and on gaps in existing advocacy provision alongside previously unconsidered geographical and service dimensions of that provision.