The foundations of this research were shaped by a group of co-applicants with lived experience;  this includes people who have lived experience of complex emotions and some who have received a BPD diagnosis. The group is supported by McPin Foundation. This group have a very strong track record of involving those with lived experience in research, under challenging  circumstances, including research designed to reduce health (and especially ethnic)  inequalities in experiences and outcomes of mental health care.  They have helped shaped the initial direction of the research and continued this role as 'co-investigators' by taking a  researcher role within this project to further support and develop it.

Peer research is a participatory research method in which people with lived experience of the issues being studied take part in directing and conducting the research. They may be involved in assisting with research design, developing research tools, collecting and analysing data, or writing up and disseminating findings.

There are many advantages to adopting a peer research approach.

• Access to ‘less heard’ voices: Because peer researchers identify with the community being studied, they can often connect with people who might be unwilling to engage with professional researchers. Peer researchers can use their networks and relationships to involve people that may not otherwise have been included in research.

• Empowerment of participants: Peer research is about conducting research ‘with and for’ the people affected. That changes the traditional power imbalance of ‘outsiders’ conducting research.

• The added value of lived experience: Peer researchers have their own lived experiences, and that knowledge and inside understanding of the issues being studied can enhance the research.

• Gathering better data: When those conducting research have experiences in common with the people they are interviewing, it reduces the risk of misunderstanding and increases the likelihood that the the conversations will be relevant to the people involved. In addition, people may respond more honestly and openly to an interviewer who has personal experience of the issue being discussed, or who they already and feel they can speak with more informally.