Dave Merritt calls on great clarity today in composing a tribute to his son, Jack, one of two young people who died on London Bridge last Friday. He rises to the sombre occasion in a way that humbles the reader.

How remarkable to think so clearly at a time of such personal loss.

Writing in the Guardian, he describes the many good qualities his son possessed – proud, “absorbingly intelligent… fiercely loyal…”

“But Jack was also angry, frustrated, selfless, stubborn. He was angry because he saw our society failing those most in need.”

He says his son would be “livid” if he could comment on his death. “We would see him ticking it over in his mind before a word was uttered between us. Jack would understand the political timing with visceral clarity.”

Jack Merritt and Saskia Jones died in the attack, killed by the knifeman Usman Khan. Both were attending a conference celebrating the fifth anniversary of the Learning Together prison programme; three other people were injured.

The tributes to Saskia, 23, were as heartfelt as those for Jack. Her family recalled her “wonderful sense of mischievous fun”, then said: “Saskia had a great passion for providing invaluable support to victims of criminal injustice.” She had, they added, recently applied to join the police graduate recruitment programme, hoping to work in victim support.

Jack’s name was the first to be released. His father pleaded in a Twitter post for politicians not to use his son’s death as an excuse for draconian action. “My son Jack would not wish his death to be used as the pretext for more draconian sentences or for detaining people unnecessarily,” he tweeted.

His plea fell on deaf ears, or on Boris Johnson’s ears. For there the prime minister was the next morning, tub-thumping in the Mail on Sunday. “Give me a majority and I’ll keep you safe from terror,” he bellowed.

Two mentions of himself in one headline.

Hard not to see that, and subsequent statements, as making political capital out of two brilliant young people who’d believed in helping others.

Politics should have gone to sleep for a day or two. Labour leader Jeremy Corbyn should have kept quiet. Instead he pointed out that he’d always said the invasion of Iraq would “set off a spiral of conflict, hate, misery, desperation…”

Never mind that Corbyn is probably right about that. It just wasn’t the time.

The greater sins of political opportunism lie with Boris Johnson and his spinners. Just look if you have the stomach at the social media ‘poster’ with Johnson waving his fist beneath the words “Tough on Terrorism” and Corbyn pictured beneath the words “Soft on Terrorists”.

And look too at the lickspittle right-wing newspapers lining up to parrot the message this morning: “New blitz on freed Jihadis” in the Mail and “Boris blitz on freed Jihadis begins” in the Express.

Look, too, at the Tories and Labour squabbling over who should be blamed for this latest atrocity (big clue, those who’ve been in power for a decade, perhaps).

The party leaders joined London Mayor Sadiq Kahn at a vigil today to mourn the victims. Afterwards, Boris Johnson slipped back into the blame game. If you wish to join me in mumbling, “How does he live with himself?”, feel free.

Politics should have taken a holiday. The politicians should have put their words back on the shelf. And the family and friends of two bright and brilliant young people should have been left to cry and to mourn.

I’ll leave the last word to Dave Merritt: “Through us all, Jack marches on. Borrow his intelligence, share his drive, feel his passion, burn with his anger, and extinguish hatred with his kindness. Never give up his fight.”