Thank you for your response, First of all, I believe that BPD and bipolar disorder or two very different things. What worked for you for treating your BPD does not automatically generalize to people with bipolar disorder. As far as I know, BPD has to do with emotion regulation, but specifically in the context of social relations. Something happened, and the person with BPD reacted to that. For bipolar disorder this is not necessarily true. Often times nothing happened and still we experience severe mood changes. Or something happened and we react in totally the opposite of what you’d expect. I personally tend to respond with mania to negative life events that really hurt me. BPD luckily tends to get milder in adulthood (around ~ 35 years symptoms tend to get milder), for bipolar disorder that does not happen.

Second, my jaw dropped when you made this statement: I strongly believe that it is much more useful that we frame the condition's aetiology in a psychological context, rather than a biological context. It is, after all, a condition of the mind, and so it is safe to assume that the fluctuations in mental/emotional states are not random neuro-chemical firings, but based around psychological triggers. I am sure that the condition likely has its roots in past trauma. “It is a condition of the mind”. No it is not. It is a condition of the brain, and we can actually measure that and see differences between people with and without bipolar disorder. Since our brain is part of our body, I regard bipolar disorder as a somatic disease. “is safe to assume that the fluctuations in mental/emotional states are not random neuro-chemical firings” I totally disagree with this. In fact, this is exactly how I explain bipolar disorder to others. I can feel really sad when my life is a fairy tale and I can get overjoyed with hypomania when the worst things have happened to me. And very very very often my mood just changes when nothing else has changed. Again, bipolar disorder is not BPD. “I am sure that the condition likely has its roots in past trauma”. Then I must be cured, because I did not experience any kind of trauma myself . Of course, any psychiatric disorder can be triggered by trauma, but that does not make trauma the ‘cause’ of the disorder as you are suggesting.
“Drugs aren't the answer - and they also hinder progress in therapy.” In the country where I live (the Netherlands) nobody receives drugs without psychological treatment. Therapy is always part of the treatment. Medicines are seen as a tool that it makes it easier to live up to the things you have learned in therapy. If you really think that drugs are unnecessary I really doubt whether you have ever seen somebody truly suffer from psychosis or severe depression. These are severe mental conditions that, if not treated with drugs, end in death.