Every two years the heads of government of the 50-plus states of which the Commonwealth consists, embracing almost a third of the planet's entire population and several of its most dynamic economies, meet to discuss issues of common concern.

Nothing unusual about that except that this year, at the recent gathering in Trinidad (called CHOGM for short), there was a significant difference.

The familiar features were certainly there, with Queen Elizabeth arriving as titular head of the Commonwealth to preside at the ceremonies and quite a lot of internal wrangling about past, future and misbehaving members — notably Zimbabwe and whether it should now be invited back into membership. This was bound to be a difficult debate as long as the dreadful President Robert Mugabe still clings to office.