The Baby and I were talking about my father, her grandfather, whom she barely knows. I was trying to remember when she had last seen him, but she was very clear.

The last time I was there, she said emphatically, was when you went to the CIA by accident.

Right. I had almost forgotten that.

I had taken the two younger children, my son the Actor (then about 15) and the Baby (10), on holiday to the USA. Among other places, we went to my father’s house in northern Virginia, partly to visit with him, and partly so I could show these British children some of their American heritage.

One morning I borrowed my father’s car just to drive it as far as the underground – I guess it was about 20 minutes. I wanted to take the kids into Washington DC.

About five minutes down the road I remembered I did not have my driver’s license with me (in England you are not required to carry it when you drive, and because it is large and doesn’t easily fit into a wallet, I usually don’t).

Oh, don’t be silly, Mother, said the Actor. You are not going to get stopped!

A few minutes later I remembered I hadn’t brought the map either, but once again my son took charge. Not a problem, he said, I’ve memorised the directions.

So we carried on. I spent the day dragging the kids to every monument and memorial in the Capital. It was post 9/11. Visits to the White House were suspended and trips up the Washington Monument had to be pre-booked, but otherwise we saw and did pretty much everything a good tourist is meant to do: we trooped up the steps of the Lincoln and Jefferson Memorials, wandered in the then fairly new sculpture garden at the Roosevelt Memorial, and walked sombrely past the names of the Vietnam dead (which I found deeply moving, and no doubt the children found dull, but they humoured me).

At the end of the day we rode the train back to Virginia and the Actor directed me as we picked up the car and headed toward my father’s house. We were nearly there when the Actor told me to take the next right.

Here? I asked.

I think so, he hesitated, and I turned. The sign, invisible from the main road, said, CIA. Authorized Personnel Only Past This Point.

Oops, said the Actor.

I looked around in a panic. The road was designed with a thick hedge of trees and bushes entirely separating the lane heading towards the CIA from the lane heading away. There were no turns to the right or left and no way to go back.

I had no choice except to carry on and eventually stop in front of a speaker on a post rather like the ones where you order at drive thrus. Only I didn’t think they would be selling me a latte. We were still a long way, I guessed, from any building.

A stern voice asked me to state my business with the CIA.

I said I didn’t have any business. I had taken a wrong turn and just wanted to get back on the main road.

The voice ordered me to continue forward into a parking area, stop in front of the chain link fence and follow the instructions of the officer.

I said, Please can’t I just turn around?

The voice bellowed, Follow the instructions of the officer!

I pulled in and parked.  Through the rear view window I saw a man in combat uniform sporting a machine gun almost as tall as he was saunter towards the car. I rolled down the window and waited for the inevitable question.

Can I see your driver’s license?

I explained that I came from England where it was not necessary to carry the license.

Okay, he said, Can I see your passport then?

I regretted that I did not have my passport with me.

He strolled around to the back of the car and examined the number plate. As he did so the Baby asked, in a whisper, What does the CIA do?

Without hesitation my son answered, They kill people.

The officer returned and said, in some exasperation, Well, can I see some kind of picture ID, please?

I said I thought I must have something… I shuffled wildly through my wallet and in a moment produced the only one with my photograph on it.

Reader, I handed the officer my Bodleian Library card.

A look of real sadness came over his face as he turned it from front to back. Ma’am, he said, I’m trying to help you here.

Well, anyway, things went from bad to worse and the officer pointed out I wasn’t giving him much to go on when I couldn’t find either the registration or insurance documents in the glove compartment. Nevertheless, he finally let us go after running the number plates to see if the address I gave him matched. You’ve got a couple of kids in the car, he said, by way of explanation, but I think it was the Bodley ID.

Back home, my father found the story hilarious. The turn towards his house is right after the CIA turn and it seems it wasn’t the first time that mistake had been made. His new house cleaner had also gone to the CIA by accident, only because she was Hispanic and driving an old beat up car, the disembodied voice directed her to pull into a spot where swords came out of the ground, surrounding the car and creating a cage. She was scared out of her wits. My father laughed until he cried as over and over he threw up his arms to demonstrate just how the swords had come up.

I guess, compared with your average encounter with the CIA, we came off pretty well.