Leading article: What are imaginary friends for?

Once psychologists believed it was a cause for concern if a child had a companion invisible to the rest of the family. But now it seems that imaginary friends are a normal part of children's development. Apparently nearly two-thirds of kids up to the age of seven have them.

You can see why a politician would find one useful. Children call on their imaginary friends when they feel upset or when someone has said something nasty to them. They give them someone to boss around when they feel powerless. Not all imaginary companions are friendly. Some are uncontrollable, which at least gives you someone to blame when the lamp in the living room is found to be broken or a particular public spending cut turns out to be rather unpopular.

The latest research also shows children do not dismiss or forget the imaginary friend as they grow older. Nine per cent still have one at the age of 12.

Perhaps David Cameron's imaginary friend is Nick Clegg. If so, the Liberal Democrat leader needs to know that the research shows a child doesn't necessarily play with the same fantasy companion throughout childhood. Some children have multiple or serial pretend friends. Sounds more and more like modern politics.