Explicit Lyrics

Does anyone know the rules regarding explicit lyrics on CDs here in the UK?

I bought the James Blunt album the other day whilst in town with my 2 year old daughter. I got in the car to drive home and thought I'd put it on. Anna-Louise is nodding her head to the music in her car seat when the word 'fucking' came out of the speakers. I turned the stereo off and waited for the inevitable "What does fucking mean daddy?" Luckily she never asked.

Now I didn't remember an explicit lyrics sticker on the case when I bought it and a check when I got home confirmed this. I examined the case closer and on the back, blended in with the other writing on there is a box warning of foul language.

I'm not complaining about it as I have been known to use the odd four letter word myself in the past, but some better sort of warning would have been nice. I thought that if there was any swearing in the lyrics, one of those black and white stickers had to be on the front of the case telling you so.

Can anyone comment?