There we were on the tarmac at Heathrow as the papal jet prepared to land. The cameras were trained on the night sky. The red carpet was rolled out. The charming Foreign Office people tried for the umpteenth time to remind me where to stand – and all the while my mind was whirring with a single question. It is a problem that goes to the heart of the relationship between church and state. It is a question that will be studied by future generations of students of theology and patristics, because the answer we give – and the answer you give, off the top of your head – is an indication of the balance currently existing between the privileges of spiritual leaders and the egalitarian demands of our temporal world.

Never mind abortion or paedophile priests. As Pope Force One taxied towards us, there was one issue still revolving in my mind at the speed of a Rolls-Royce fan jet. Should the Popemobile be liable for the congestion charge and, if not, why not? Should the Holy Father have to pay £8 to drive through Westminster, like everyone else? Or should that fee be waived, in recognition of his status as the vicar of Christ on Earth? It is a tough one, and I am sure there will be clear-sighted readers of this paper who will take opposite views; and it is that very division of instinct that is so revealing about the psychology of this country.