Update at lunchtime on Wednesday 2 December - I understand that an investigation is now underway and shall refrain from further comment on this blog about the matters under investigation. UNISON has an opportunity now to deal with matters appropriately.
Update on 23 December - having just now responded to a comment on this post I have taken the opportunity to correct the wording above. There have been considerable further developments since this post was written (not least the declaration of the result of the General Secretary election) but also the internal investigation (which is now underway). It would be wrong to presume the guilt of any party but, in particular, I do not assume that the General Secretary himself was personally aware of anything just because the person speaking in the recording of the meeting sought to imply that he was. I have not made that assumption in calling for a thorough investigation of evidence which is certainly of concern, and I would not encourage anyone else to make that assumption.