I'm a volunteer in a charity shop and we have a new (and somewhat over-zealous) volunteer in our shop.
I was sorting clothing yesterday and came across a bag where all the labels had been cut out - people do this quite often. Over-zealous volunteer confidently proclaims that it's illegal to sell clothing without the care label on it. It's a legal requirement to let people know what the garment is made of, the composition of the fabric, the washing instructions. And if we can't do that, we are breaking the law by selling that item of clothing. 
I've been volunteering for 5 years in one of the major chains and nobody (volunteer or paid staff) has ever said this to me before. We sell things like handknits which are obviously not labelled, vintage clothing, clothing made overseas which don't have the same labels as those in the UK. We're aware that there are different rules for toys and children's nightwear and dressing up clothes, and never sell without the CE label.
But is is really a legal requirement for second hand, adult clothing?