Boris Johnson yesterday wrote to French president Emmanuel Macron suggesting escalated measures to stop the deadly human traffic between Calais and Kent.

As voters in both France and Britain asked themselves how this terrible tragedy could have happened, the letter might be read as a nudge to the French, who have not merely been turning a blind eye to people smuggling, but essentially forcing migrants into the embrace of the passeurs by bulldozing shantytowns.

‘As I set out in a letter to you this summer, I have long been profoundly concerned that any morning, we could wake to the news of a serious tragedy involving widespread loss of life in the Channel, including of women and children. Such a catastrophe has now happened,’ the PM said.

Boris suggested joint maritime patrols, stepped up surveillance and better intelligence targeting the people smugglers. The French responded with a renewed and intensified round of Macron’s signature tantrum diplomacy.

Last night, Macron refused to accept the slightest responsibility for the Channel tragedy, in which 27 migrants – including a pregnant woman and three children – perished. The accident happened just hours after a boat was watched heading into the water by French police.

Macron went on to suggest the tragedy (that occurred in French territorial waters) was the fault of the UK and warned Johnson to refrain from politicising the catastrophe. Gerald Darmanin, the French interior minister, was so insulted that he has cancelled the visit of his British counterpart, Priti Patel, who had been scheduled to visit Calais this afternoon.

By this morning, on a visit to Italy, Macron was seething:

I’m surprised when things are not done seriously. We don’t communicate between leaders via tweets or published letters, we are not whistle blowers.

After all, what’s more important? French feelings or dead children in the Channel?

Predictably, the ranks of British remainers and their media soup servers have been quick to join the pile on, blaming Britain for the incompetence of French police. This morning, Sophie Pedder, bureau chief of the Economist in Paris, admiring biographer of Macron and author of her magazine’s cover story depicting Macron walking on water, declared:

If you tried to write a letter to irritate France, this would be it. 1. Self-congratulate and take moral high ground. 2. Make letter public, to enhance 1. 3. Tell France and EU to do more to patrol a border that the UK left EU in order to regain control over. Breathtaking;.

Writing this morning in the Daily Mail, I wondered if Macron’s fury over Brexit and desire to punish the British for our insolence in leaving his beloved EU might have been behind his readiness to turn a blind eye to the flotillas of inflatables crossing the Channel. The French authorities have not seriously attempted to stop this.

This story is rapidly changing. French fishermen are threatening blockades of ports and the tunnel. There is a febrile presidential election campaign underway. Macron is pressuring Britain on Ireland, on fish and on migrants. And the Channel might soon be blockaded. Downing Street’s cunning plan to reset relations with France, leaked only last weekend in the Sunday Times, doesn’t seem to have made it to the end of the week.