A mic inadvertently live from another studio - intruding into a live broadcast. It's happened to us all - but this incident did seem to take a worryingly long time to sort out, bearing in mind BBC Radio 4 production resource.
As heard on You and Yours on 16th Oct 2019.
Warning - expletive.
Read my view here on the broader issue.
https://www.davidlloydradio.com/post/it-s-xxxxxxx-cold-in-this-studio