Today Kabul city is getting a new lick of paint. This isn’t a celebration but because the new rulers have banned photographs. All billboards, shop fronts and public spaces in a town half the size of London will lose their colour and blank walls will replace glamour models.

That’s not the worst of it. Underneath the white hoardings, pools of red are forming. The Taliban, despite its promises, have begun the executions that were long predicted and have been seen in Lashkar Gah and other towns it has captured. This is heart-breaking for everyone but perhaps more so for those of us who know the place and the people.

Like all the best cities, it has everything. Markets, food, confusion, noise and people from around the world. Pashtuns mix with Tajiks, Uzbeks, Turkmen, Baloch, even some Sikhs, each bringing their own style and culture. When I lived there, helping to set up the Afghan National Security Council, my Afghan colleagues each had their favourite haunts. Restaurants — and even secret bars that served illegal alcohol — were where we went after work to talk about everything and the old days: life under the old king, the communist period and now the American period, as they called it. It was fascinating to hear.

My favourites were the Hazara places. Delicious ravioli-like pasta filled with lamb and covered in yoghurt, called mantu, came out of bamboo steamers like so much eastern cooking. Those restaurants will be closed now. Their owners have faced frequent persecution from the Taliban in the years before the Nato operation in 2001. Today, the new government will have a completely free hand, there isn’t even the Northern Alliance to offer sanctuary.

This is a tragedy of our own making. We’ve pulled out the keystone of a complex security triangle and are now watching the effect. It’s a choice. It’s our choice. But let’s not pretend it had to happen. As we start getting reports of executions on the street of those who worked with us or the Afghan government, the brutality towards women and the persecution of the Hazara, remember, this is because of the choice not to redeploy 2,500 troops.

That’s about half what you need on an aircraft carrier, about eight per cent of the troops in the Gulf, and a fraction of those in South Korea and Japan where they have been for decades.

They weren’t fighting. No British soldier had been killed in combat since 2013. They were holding the line. Now that’s over. Over the coming weeks we’re going to see this tragedy unfold — we’ll witness the hangings on TikTok. Twitter will bring reports of massacres. When you see them remember, the cost of the continued operation was low. And my friends who we lost are never coming back. This was a choice. President Biden chose to leave. Everything that now follows was foretold.