The "F word" is permitted. Hell, we even have a programme
called "The F Word", hosted by good 'ole Gordon Ramsey.
WPC (Woman Police Constable) was taken out of use following the whole equal rights charade that occurred during the olden days. It's often frowned upon to use such words nowadays in our increasing PC society. I'm not a PC person myself, I was just suprised that the BBC had a moment of being un-PC.
I wish they were more un-PC on stuff that actually mattered.