Funding for this research was provided by:
National Institute for Health Research Policy Research Programme (PR-UN-0409-10109)
Received: 30 September 2019
Accepted: 13 November 2019
First Online: 27 November 2019
Ethics approval and consent to participate
: Approved by the Psychology Research Ethics Committee of the University of Cambridge (Reference Number: PRE.2017.029). Consent was not required; customers were not informed of the study taking place.
: Not applicable.
: The authors declare that they have no competing interests.