Iyengar‘s 1984 yoga demo at the Barbican, London

I’ve been seeing a lot of video clips of Iyengar demonstrating asana as well as giving speeches/lectures about yoga philosophy.

What I have not been able to figure out yet is the background of this happening? As in: what kind of event was this and who were the audience? What was it promoted as? Was it part of a broader event?

Can anyone shed some more light here?