Senior insiders admit concern about big editorial errors and fear attacks are part of ongoing campaign to undermine the broadcaster

There is a joke regularly deployed by BBC staff that “deputy heads must roll” over big mistakes because they rarely appear to have any impact on those at the top of the organisation. That all changed on Sunday, when Tim Davie and Deborah Turness both quit their jobs.

Davie oversaw no shortage of scandals during his five years as director general – in recent months these included rows over a Gaza documentary and Glastonbury coverage – and was nicknamed “Teflon Tim” by BBC insiders because nothing seemed to stick.

But this week, it did.

Odd, though, that the trigger for this crisis was a largely forgotten report by the Panorama programme, broadcast more than a year ago, about the US election.