For me, If I had been SJ BM with the beauty of hindsight!! ( although may have amounted to nothing)
Julie approaches EP, confesses all about JB.
Stan " Julie ring JB, get talking about events " " we will record the conversation "
Julie rings Bamber on the normal pretext, discusses current events ( gets Bamber to make an admission on the phone that can be recorded)
Admission made, strong evidence.
That simple.
Did SJ miss a trick?