1. Division of Psychiatry, Imperial College London, London, United Kingdom
2. Play in Education, Development, and Learning (PEDAL) Research Centre, Faculty of Education, University of Cambridge, Cambridge, United Kingdom
3. School of Public Health, Imperial College London, London, United Kingdom
4. Imperial Clinical Trials Unit, Imperial College London, London, United Kingdom
5. Clinical Child and Family Studies, Faculty of Behavioural and Movement Sciences, Vrije Universiteit Amsterdam, Amsterdam, the Netherlands
6. Institute of Psychology, Psychiatry, and Neuroscience, King’s College London, London, United Kingdom
7. School of Psychology, University of Surrey, Guildford, United Kingdom
8. Parent Supporter Service, Netmums, London, United Kingdom
9. Department of Psychiatry, University of Oxford, Oxford, United Kingdom
10. African Health Research Institute, Durban, South Africa
11. Department of Psychology, Education, and Child Studies, Erasmus University Rotterdam, Rotterdam, the Netherlands
12. Warwick Clinical Trials Unit, University of Warwick, Coventry, United Kingdom