John Carey spent £50 a month feeding his habit.

But it wasn't cigarettes, beer or drugs taking its toll on his wallet - it was plastic ballpoint pens.

John couldn't stop himself nibbling them to pieces at work, often ending up with ink all over his face.

It became such a compulsion that his boss took him aside and told him to buy his own because nobody else in the office could find a pen without teeth marks in it.

Now, after undergoing a hypnotherapy course, John is cured but while that is good news for him, shares in pens have probably slumped due to a substantial reduction in demand.