Seeing John Cole (then of the Observer) appear as a pundit prompts two points:
I don't recall any outcry or accusation of bias against John Cole when he was BBC Political Editor despite the Observer (of which he was Deputy Editor) having backed Labour in the election.
The then Political Editor in 1979, apparently David Holmes, doesn't seem to have taken part in the Election programme, which would be unthinkable these days. Possibly a symptom of BBC News and BBC Current Affairs being separate entities then, and this looks a lot like a Current Affairs production with a bit of news input from Angela Rippon?
Write that down in your copybook now.