What the legal people are saying is that the BBC is likely to be held vicariously liable. I don't think vicarious liability would apply to Ken or Maggie in that sense. The BBC as his employer would be held vicariously liable.
http://www.bbc.co.uk/news/entertainment-arts-19925344
Here's a good example of vicarious liability under similar circumstances at a boys school:
http://www.guardian.co.uk/law/2010/o...iability-abuse