2.1. Services

Data were provided by eight Improving Access to Psychological Therapies (IAPT) services based in London, England. These National Health Service (NHS) primary care and community-based mental health teams deliver evidence-based psychological therapies for depression and anxiety disorders. They offer a range of low-intensity (LI) treatments such as guided self-help, and formal high intensity (HI) psychological interventions such as cognitive behaviour therapy or counselling, all delivered utilising a stepped-care model in line with national guidelines and evidence-based practice (see (Clark, 2018) for more details). All services were members of the North and Central East London IAPT Service Improvement and Research Network (NCEL IAPT SIRN) (Saunders et al., 2020).