Cadbury's shrinks chocolate bars: is it fair?

Dairy Milk
Dairy Milk

eff Moore/Jeff Moore/Empics Entertainment

It's not just Willy Wonka flogging shrinking chocolate bars: Cadbury's is getting in on the act. It has shrunk the size of its classic chocolate bar from 49g and 45g. What's worse is the fact that the price of the bar has stayed exactly the same - at 59p.

So what's going on? And can this be fair?