All of the cheese and most of the onion land on my groin. I curse. The motorway has been clogged all the way from London. I've driven less than 100 miles in two hours. I've already spilled the tea and now my sandwich has collapsed. Perhaps I shouldn't have set out during one of the great migrations of early 21st-century British life - half-term.
Across our tarmac-traced nation, millions are trundling towards their destinations. But these millions must stop on the way. Dotted with the remains of my lunch, I pull in to a service station. The car park is full, but the people carriers, 4x4s and superminis are empty. Where is everyone? I find the answer inside. Hundreds of people are thronging the shops and food counters that edge gaudily around an atrium filled with plastic tables and chairs, between which dispirited Midland teens push brooms.
Apart from them, everyone in here - on their way to visit in-laws or to spend four days in a glass dome enclosing withered pine trees on the edge of East Anglia, where the children will run wild and the parents drink themselves senseless in themed restaurants - appears content. These are the English en route, a nation on the move, though right now, despite the football shirts made from sparkling man-made fibres, there isn't much movement going on. The pace is gentle, an ambling graze, not on sandwiches and metallic tea from Thermos flasks, but sugared carbohydrates and fried proteins piled on plastic trays.
The children are plugged into machines, either the small electronic ones they carry with them or, in the service station galleries, bigger machines they can get their entire bodies into. Stuffed with food, the fathers recline and scan the Express, the mothers shout into mobile phones and the smaller children slump into sleep. These are the people who voted for Blair, and the people who - if they can be persuaded - will give victory to the Tories next year.
David Cameron knows this, but as much as he makes a point of acknowledging their cultural lodestars, dragging his wife to The Lion King, the real home of his quarry is here, the motorway service station, repository of the travellers' desires: Dan Brown, McDonald's, a shop selling discounted techno CDs. This, I realise, is no longer a stopover. It is a destination.
I go back to the car and pour the last of my tea. I am alone, apart from a man who is walking his dog. They approach a dead sapling, stranded on the muddy bank that shields us from the motorway. The dog shits and they walk away.