We don’t often have a family dinner at Brooks’s. If the three of us are having dinner together in London, I tend to vote for a place where the menu has such exotic ingredients as lemons, olive oil, garlic and basil. A place where all the women wear black trousers, interesting tops and necklaces made out of pebbles, and the men wear open-neck shirts. But, when it’s deemed a special occasion, only the familiar ritual of a glass of Champagne in the green library, followed by dinner in the peach-coloured dining room, is considered mile-stoney enough. Which is why we’re having
dinner there tonight.

You might think it’s grasping at occasions to have a dinner simply because the 20-year old son is going off for the summer. ‘He’s not going to Afghanistan,’ my sister’s email snapped back when I sent her a nervous description of his itinerary. But I’m no Freya Stark and the destinations Damascus, Beirut and Jerusalem seem sufficiently foreign and redolent of turmoil for me to feel my usual Traveller’s Unease.

In fact, it isn’t so much the destinations that make this feel like a significant journey. It’s the realisation that it’s the end of an era. The end of loading the car with guns, dogs and fishing rods the night before, and getting up at dawn to head for Scotland. The end of trips to visit the Old Ancients in Mississippi, where the highlight of the holiday was looking out for water moccasins while fishing for catfish in the Tallahatchie. The end of going crazy over what to do and where to go for the Family Holiday.

In many ways, it feels like early retirement. This summer, Sam has made all the arrangements tickets, visas, places to stay, jobs without any help from the Trip Planner called Mama. All I’ve managed to contribute to this sojourn are featherweight khakis from Orvis and a small pharmacy from Boots, products to ward against skin cancer, toothache, stomach pain, heat rash and wasting disease.

I tried to sneak in the best before-2007 Tamiflu, but the prodigal son assured me that swine flu is the least of the troubles in the Middle East. He tolerates this Old Testament Christian, the wild-eyed woman who warns that the feast will be punished if you eat the melons and tomatoes, ‘because they are full of water. Polluted water!’ But I am confused by my redundancy. Like many in the maternal workforce, I thought I was irreplaceable.

Meanwhile, the son’s absence will leave a vacuum. We’ll spend our summer evenings pouring over old maps, tracing his footsteps, waiting for the telephone to ring, and accepting that a phase of our family history is over. Not that we won’t have the odd week of the summer all together, but the long summer days that used to stretch out like a river will now be filled with his friends and contemporaries.

‘Buck up,’ my sister writes. ‘Now you can go places whenever you want, not just during the school holidays. You can go to more exotic places, stay in good hotels and eat in better restaurants.’ Our friends who rented the same damp cottage in Cornwall for 20 years tell me they now spend a week in September on the Ile de Ré instead. They eat lobsters instead of chicken wings and drink Sancerre instead of Chilean Chardonnay. Best of all, they say, they no longer come home exhausted.

This sounds good, of course, and I’ve suddenly noticed that the Eurostar ads look as if they’re using the same models who pose for Saga Holidays. It’s not that I’m reluctant to pass the torch to a new generation and never again fly on a budget airline, it’s just that I didn’t see it coming. All the same, tonight we can toast to the traveller. Who is leaving at 4am for Heathrow and a 6:55am flight. Who will arrive in a city that is 104˚F. Who will stay in a hostel that costs €25 a night. We will miss him, and, with any luck, he will be glad to come home.