Funding for this research was provided by:
Programme Development Grants (HPRU-2012-10047)
Economic and Social Research Council (ES/P008313/1)
Received: 25 June 2019
Accepted: 30 August 2019
First Online: 13 September 2019
Ethics approval and consent to participate
: Ethical approval for this study was granted by National Health Service (NHS) (England) Research Ethics Committee (IRAS ID 176038).
: Not applicable.
: The authors declare that they have no competing interests.