Nine interviews were carried out with UK public health practitioners, researchers, and policymakers between 2013 and 2016.

The following reasons for choosing WEMWBS were elicited:

Filling a gap

[WEMWBS] can fill that space between measures which are about quality of life and … measures which are purely about anxiety and depression …. and I think that’s really where it has its strength.” -Civil servant.

• measurement of the positive:

“We were just desperate for a measure that recognised positive mental health and wellbeing.” -Independent mental health specialist.

• asset-based approaches which focused on:

“Positive and protective factors’ […] rather than seeing a load of people that needed help [ ……they] saw loads of good things […] and could work on and encourage more.” -PHE Employee 1.

• changes in mental health to be captured alongside biomedical outcomes. For example, in a weight management programme, including evaluation of how participants felt holistically:

“You’ve lost 10lb or 20lb - and how do you feel physically? how do you feel mentally? what’s that done for you and your confidence?” -Clinical commissioning group and local authority employee.

• better alignment with participants’ frame of reference:

“Undoing some of the damage done by their experience of being measured by clinicians in terms that they don’t understand, not because they’re stupid but because the frame of reference doesn’t have meaning for them.” -Community and voluntary sector employee.

Enabling understanding and credibility of mental wellbeing

Participants recognised that mental wellbeing was still a contested area for some of their colleagues.

Hey just didn’t see the relevance of it for them… there was a kind of bewilderment, I suppose.’’ -PHE employee 2.
“Wellbeing can be interpreted as a kind of fluffy nonsensical thing.” -Researcher.

In this context, they believed WEMWBS to have made:

“A huge contribution to that shift in understanding and accepting that mental wellbeing is something tangible that can be measured and therefore we can do something about it.” -Public Health England employee.

And facilitated a change in emphasis in practice:

“[We were] asking GPs […to] signpost them onto improving their resilience and wellbeing […] that wouldn’t have happened in my opinion if we hadn’t had the WEMWBS.” -General Practitioner.

-not by requiring change, but by enabling practitioners and researchers to find out for themselves:

“… repeated exposure and people being able to measure it and do it for themselves, do it in their own practice in their own time, can develop their own ideas about how helpful or not it is.” -Researcher.

The act of using WEMWBS seemed to open up discussions around mental wellbeing and its importance, at politico-organisational, community and individual levels. The measurement of mental wellbeing was said to enhance both the credibility of interventions and that of the practitioner or researcher using it:

“Before WEMWBS it was easier to dismiss us as woolly … it’s given us some credence.” -Independent mental health specialist.

Providing a common currency

Another important contribution covered by many participants was that WEMWBS provided a currency which could enable comparison across a wide range of activities offered by non-government organisations (NGOs) as well as public services and in different settings and sectors.

Often when they [smaller organisations] do define impact it’s in lots of different currencies… and the power of {mental] wellbeing really is that you can have it as a common currency of social impact across so many diverse forms of activity, and I think that’s the power behind it really.” -Civil servant.

Examples were cited of successful bids for new projects based upon WEMWBS outcome data, and the way it could contribute to policy development, giving credibility to low cost, non-clinical interventions. Examples of projects included peer support and self-management intervention, a wellbeing pledge programme, parenting interventions, knitting, and art therapy.

“It has been used [.. ] in evaluations to measure the impact of policies; […that] helps to make the case next time around on either scaling or broadening the intervention.” -Civil servant.

Well validated, respected and widely recognised

Although participants were aware that there was still some uncertainty about the validity of the evidence:

I still come across pockets of academia that say ‘the science behind it isn’t there’, ‘but that’s not based on anything, that’s just people’s opinions when you speak to them.’’ -Clinical commissioning group and local authority employee.

-they recognised both the quality of the validation studies:

“We know that it’s got the scientific backing, the evidence backing so we’ve just kind of said this is what we’re using, this is the tool we’re using.’ -Clinical commissioning group and local authority employee.

-and widespread recognition of the measures:

“It’s no longer an interesting distraction from work, it’s an integral part of what we do now.” -GP.

“[WEMWBS] seems to be the measurement tool [that is] nationally recognised.” -Clinical commissioning group and local authority employee.

Participants suggested that the dissemination of WEMWBS had occurred through a mix of bottom-up and top-down approaches. Use was perceived to have spread by word of mouth and electronic searching rather than in evaluation guidelines, in order to strengthen business cases, convince decision-makers and secure funding. Both in clinical services and in community organisations use of WEMWBS was often a pragmatic response to an external mandate to evaluate from funding sources. This was accompanied by wellbeing champions pushing for use at local and national levels and through the requirements of commissioners to evaluate programmes to support performance management.