I’ve lived in the US for 20 years and mass shootings – even the unspeakable slaughter at the Pulse club in Orlando, Florida last weekend – by now almost numb the senses. They are so frequent, so pointless and so similar, rituals of heartbreak for so many people – they change nothing. Indeed the most discernible effect of each new horror is merely a boost in gun sales in the days and weeks that follow.

Not so the murder of Jo Cox. Truly it shocked. Britain is a place where such things supposedly don’t happen. Not in our placid and level-headed country, where legend has it that you can more easily win the lottery than get hold of a handgun. Unlike America, where four presidents were assassinated inside a century, and where politicians in thrall to the National Rifle Association fight to preserve the constitutional right of deranged individuals to own the assault rifles whose sole purpose is killing as many people as possible in as short a time as possible.

Contrary to legend, Britain has, needless to say, experienced its own mass shootings (Hungerford and Dunblane, anyone?) and its political murders – most recently the death of Tory MP Ian Gow at the hands of IRA car bombers in 1990.

Jo Cox: Tributes to the Labour MP

Years ago, I used to watch Charlton Athletic. Close to the football ground stands a handsome brick parish church of St Luke, and out of curiosity one day I dropped in. There I found the final resting place of Spencer Perceval, the only British prime minister to be assassinated, shot dead in the House of Commons lobby in 1812 by John Bellingham, a businessman with a grievance against the government.

But however dreadful, what happened on Thursday was most un-American in its intimacy. It happened not in London but outside a small public library, where the Labour MP was holding a routine surgery with constituents. And the number of victims was only one: thank God AK-15s aren’t available to one and all in England.

Now several aspects of the Cox murder have yet to be explained. Was it because of Brexit, and her support for EU membership and for the cause of refugees? Or did her killer have some other form of grievance, even personal – or did she simply have the bad luck to be in the wrong place at the wrong time?

Nonetheless, there are enough similarities with what happens daily here in the US to make one uneasy. The suspect in the Cox killing seems to have a history of mental problems, as well as sympathy with extreme right groups and causes – both common traits in America’s gun killers. According to some witnesses he was shouting ‘Britain first,’ as he stabbed and shot the MP. If so, then maybe we are beginning to import yet another enduring US product – that of making politics lethally personal.

It’s more than half a century since the last presidential assassination. But in 1968 both JFK’s brother Robert, who might well have become president, and Martin Luther King, a more consequential figure than almost every president, were gunned down. Four years later George Wallace, the segregationist southern governor who twice sought the Oval Office, was left permanently paralysed by an assassination attempt.

In 1981, John Hinkley came desperately close to killing Ronald Reagan. Mercifully, nothing has happened to Barack Obama despite the loathing the first black occupant of the White House inspires in some quarters. But politicians are in the gunmen’s sights: just ask former Congresswoman Gabby Giffords, America’s closest equivalent to Jo Cox, who in 2011 was fired upon by a schizophrenic as she attended a meeting with voters in her Arizona district. Although grievously wounded to the head, she miraculously survived.

In pictures: The victims of the Orlando shooting Show all 44 1 /44 In pictures: The victims of the Orlando shooting In pictures: The victims of the Orlando shooting Frank Escalante This undated photo shows Frank Hernandez, one of the people killed in the Pulse nightclub in Orlando, Fla., early Sunday, June 12, 2016. A gunman wielding an assault-type rifle and a handgun opened fire inside the nightclub, killing dozens in the worst mass shooting in modern U.S. history. (Facebook via AP) AP In pictures: The victims of the Orlando shooting Luis Daniel Conde This undated photo shows Luis Daniel Conde, one of the people killed in the Pulse nightclub in Orlando, Fla., early Sunday, June 12, 2016. A gunman wielding an assault-type rifle and a handgun opened fire inside the nightclub, killing dozens in the worst mass shooting in modern U.S. history. (Facebook via AP) AP In pictures: The victims of the Orlando shooting Brenda Lee Marquez McCool In pictures: The victims of the Orlando shooting Yilmary Rodriguez Solivan CORRECTS FROM YILMARY RODRIGUEZ SULIVAN TO YILMARY RODRIGUEZ SOLIVAN- This undated photo shows Yilmary Rodriguez Solivan, one of the people killed in the Pulse nightclub in Orlando, Fla., early Sunday, June 12, 2016. A gunman wielding an assault-type rifle and a handgun opened fire inside the nightclub, killing dozens in the worst mass shooting in modern U.S. history. (Facebook via AP) AP In pictures: The victims of the Orlando shooting Joel Rayon Paniagua This photo shows Joel Rayon Paniagua, one of the people killed in the Pulse nightclub in Orlando, Fla., early Sunday, June 12, 2016. A gunman wielding an assault-type rifle and a handgun opened fire inside the nightclub, killing dozens in the worst mass shooting in modern U.S. history. (Facebook via AP) AP In pictures: The victims of the Orlando shooting Jerald Arthur Wright This undated photo shows Jerald Arthur Wright, one of the people killed in the Pulse nightclub in Orlando, Fla., early Sunday, June 12, 2016. A gunman wielding an assault-type rifle and a handgun opened fire inside the nightclub, killing dozens in the worst mass shooting in modern U.S. history. (Facebook via AP) AP In pictures: The victims of the Orlando shooting Paul Terrell Henry This undated photo shows Paul Terrell Henry, one of the people killed in the Pulse nightclub in Orlando, Fla., early Sunday, June 12, 2016. A gunman wielding an assault-type rifle and a handgun opened fire inside the nightclub, killing dozens in the worst mass shooting in modern U.S. history. (Facebook via AP) AP In pictures: The victims of the Orlando shooting Shane Evan Tomlinson This undated photo shows Shane Evan Tomlinson, one of the people killed in the Pulse nightclub in Orlando, Fla., early Sunday, June 12, 2016. A gunman wielding an assault-type rifle and a handgun opened fire inside the nightclub, killing dozens in the worst mass shooting in modern U.S. history. (Facebook via AP) AP In pictures: The victims of the Orlando shooting Antonio Davon Brown This undated photo shows Antonio Davon Brown, one of the people killed in the Pulse nightclub in Orlando, Fla., early Sunday, June 12, 2016. A gunman wielding an assault-type rifle and a handgun opened fire inside the nightclub, killing dozens in the worst mass shooting in modern U.S. history. (Facebook via AP) AP In pictures: The victims of the Orlando shooting Jason Benjamin Josaphat This undated photo shows Jason Benjamin Josaphat, one of the people killed in the Pulse nightclub in Orlando, Fla., early Sunday, June 12, 2016. A gunman wielding an assault-type rifle and a handgun opened fire inside the nightclub, killing dozens in the worst mass shooting in modern U.S. history. (Facebook via AP) AP In pictures: The victims of the Orlando shooting Enrique L. Rios, Jr. This undated photo shows Enrique L. Rios, Jr., one of the people killed in the Pulse nightclub in Orlando, Fla., early Sunday, June 12, 2016. A gunman wielding an assault-type rifle and a handgun opened fire inside the nightclub, killing dozens in the worst mass shooting in modern U.S. history. (Facebook via AP) AP In pictures: The victims of the Orlando shooting Darryl Roman Burt This undated photo shows Darryl Roman Burt II, one of the people killed in the Pulse nightclub in Orlando, Fla., early Sunday, June 12, 2016. A gunman wielding an assault-type rifle and a handgun opened fire inside the nightclub, killing dozens in the worst mass shooting in modern U.S. history. (Facebook via AP) AP In pictures: The victims of the Orlando shooting Cory James Connell An undated photo from the Facebook account of Cory James Connell, who police identified as one of the victims of the shooting massacre that happened at the Pulse nightclub of Orlando, Florida, on June 12, 2016. Cory Connell via Facebook/Handout via REUTERS ATTENTION EDITORS - THIS IMAGE WAS PROVIDED BY A THIRD PARTY. EDITORIAL USE ONLY. NO RESALES. NO ARCHIVE. REUTERS In pictures: The victims of the Orlando shooting Tevin Eugene Crosby This undated photo shows Tevin Eugene Crosby, one of the people killed in the Pulse nightclub in Orlando, Fla., early Sunday, June 12, 2016. A gunman wielding an assault-type rifle and a handgun opened fire inside the nightclub, killing dozens in the worst mass shooting in modern U.S. history. (Facebook via AP) AP In pictures: The victims of the Orlando shooting Jonathan Antonio Camuy-Vega This undated photo shows Jonathan Antonio Camuy Vega, one of the people killed in the Pulse nightclub in Orlando, Fla., early Sunday, June 12, 2016. A gunman wielding an assault-type rifle and a handgun opened fire inside the nightclub, killing dozens in the worst mass shooting in modern U.S. history. (Facebook via AP) AP In pictures: The victims of the Orlando shooting Rodolfo Ayala-Ayala This undated photo shows Rodolfo Ayala-Ayala, one of the people killed in the Pulse nightclub in Orlando, Fla., early Sunday, June 12, 2016. A gunman wielding an assault-type rifle and a handgun opened fire inside the nightclub, killing dozens in the worst mass shooting in modern U.S. history. (Facebook via AP) AP In pictures: The victims of the Orlando shooting Leroy Valentin Fernandez This undated photo shows Leroy Valentin Fernandez, one of the people killed in the Pulse nightclub in Orlando, Fla., early Sunday, June 12, 2016. A gunman wielding an assault-type rifle and a handgun opened fire inside the nightclub, killing dozens in the worst mass shooting in modern U.S. history. (Instagram via AP) AP In pictures: The victims of the Orlando shooting Christopher Andrew Leinonen This undated photo shows Christopher Andrew Leinonen, right, one of the people killed in the Pulse nightclub in Orlando, Fla., early Sunday, June 12, 2016. A gunman wielding an assault-type rifle and a handgun opened fire inside the nightclub, killing dozens in the worst mass shooting in modern U.S. history. The man at left is unidentified. (Facebook via AP) AP In pictures: The victims of the Orlando shooting Angel L. Candelario-Padro This undated photo shows Angel L. Candelario-Padro, one of the people killed in the Pulse nightclub in Orlando, Fla., early Sunday, June 12, 2016. A gunman wielding an assault-type rifle and a handgun opened fire inside the nightclub, killing dozens in the worst mass shooting in modern U.S. history. (Facebook via AP) AP In pictures: The victims of the Orlando shooting Simon Adrian Carrillo-Fernande This undated photo shows Simon Adrian Carrillo Fernandez, one of the people killed in the Pulse nightclub in Orlando, Fla., early Sunday, June 12, 2016. A gunman wielding an assault-type rifle and a handgun opened fire inside the nightclub, killing dozens in the worst mass shooting in modern U.S. history. (Facebook via AP) AP In pictures: The victims of the Orlando shooting Christopher Joseph Sanfeliz An undated photo from the Facebook account of Christopher Joseph Sanfeliz, who police identified as one of the victims of the shooting massacre that happened at the Pulse nightclub of Orlando, Florida, on June 12, 2016. Christopher Joseph Sanfeliz via Facebook/Handout via REUTERS ATTENTION EDITORS - THIS IMAGE WAS PRIVIDED BY A THIRD PARTY. EDITORIAL USE ONLY. NO RESALES. NO ARCHIVE. REUTERS In pictures: The victims of the Orlando shooting Javier Jorge-Reyes This undated photo shows Javier Jorge-Reyes, one of the people killed in the Pulse nightclub in Orlando, Fla., early Sunday, June 12, 2016. A gunman wielding an assault-type rifle and a handgun opened fire inside the nightclub, killing dozens in the worst mass shooting in modern U.S. history. (Facebook via AP) AP In pictures: The victims of the Orlando shooting Gilberto Ramon Silva-Menendez This undated photo shows Gilberto Ramon Silva Menendez, one of the people killed in the Pulse nightclub in Orlando, Fla., early Sunday, June 12, 2016. A gunman wielding an assault-type rifle and a handgun opened fire inside the nightclub, killing dozens in the worst mass shooting in modern U.S. history. (Facebook via AP) AP In pictures: The victims of the Orlando shooting Juan P. Rivera-Velazquez This undated photo shows Juan P. Rivera Velazquez, one of the people killed in the Pulse nightclub in Orlando, Fla., early Sunday, June 12, 2016. A gunman wielding an assault-type rifle and a handgun opened fire inside the nightclub, killing dozens in the worst mass shooting in modern U.S. history. (Facebook via AP) AP In pictures: The victims of the Orlando shooting Miguel Angel Honorato This undated photo provided by Jose Honorato shows his brother Miguel Angel Honorato, center, one of the people killed in the Pulse nightclub in Orlando, Fla., early Sunday, June 12, 2016. A gunman wielding an assault-type rifle and a handgun opened fire inside the nightclub, killing dozens in the worst mass shooting in modern U.S. history. (Courtesy of Jose Honorato via AP) AP In pictures: The victims of the Orlando shooting Jean Carlos Mendez Perez An undated photo from the Facebook account of Jean Carlos Mendez Perez, who police identified as one of the victims of the shooting massacre that happened at the Pulse nightclub of Orlando, Florida, on June 12, 2016. Jean Mendez via Facebook/Handout via REUTERS ATTENTION EDITORS - THIS IMAGE WAS PRIVIDED BY A THIRD PARTY. EDITORIAL USE ONLY. NO RESALES. NO ARCHIVE. REUTERS In pictures: The victims of the Orlando shooting Mercedez Marisol Flores An undated photo from the Facebook account of Mercedez Marisol Flores, who police identified as one of the victims of the shooting massacre that happened at the Pulse nightclub of Orlando, Florida, on June 12, 2016. Mercedez Flores via Facebook/Handout via REUTERS ATTENTION EDITORS - THIS IMAGE WAS PRIVIDED BY A THIRD PARTY. EDITORIAL USE ONLY. NO RESALES. NO ARCHIVE. REUTERS In pictures: The victims of the Orlando shooting Xavier Emmanuel Serrano Rosado An undated photo from the Facebook account of Xavier Emmanuel Serrano Rosado, who police identified as one of the victims of the shooting massacre that happened at the Pulse nightclub of Orlando, Florida, on June 12, 2016. Xavier E. Serrano via Facebook/Handout via REUTERS ATTENTION EDITORS - THIS IMAGE WAS PRIVIDED BY A THIRD PARTY. EDITORIAL USE ONLY. NO RESALES. NO ARCHIVE. REUTERS In pictures: The victims of the Orlando shooting Anthony Luis Laureano Disla An undated photo from the Facebook account of Anthony Luis Laureano Disla, who police identified as one of the victims of the shooting massacre that happened at the Pulse nightclub of Orlando, Florida, on June 12, 2016. Anthony Laureano via Facebook/Handout via REUTERS ATTENTION EDITORS - THIS IMAGE WAS PRIVIDED BY A THIRD PARTY. EDITORIAL USE ONLY. NO RESALES. NO ARCHIVE. REUTERS In pictures: The victims of the Orlando shooting Franky Jimmy De Jesus Velazquez An undated photo from the Facebook account of Franky Jimmy De Jesus Velazquez, who police identified as one of the victims of the shooting massacre that happened at the Pulse nightclub of Orlando, Florida, on June 12, 2016. Jimmy De Jesus via Facebook/Handout via REUTERS ATTENTION EDITORS - THIS IMAGE WAS PRIVIDED BY A THIRD PARTY. EDITORIAL USE ONLY. NO RESALES. NO ARCHIVE. REUTERS In pictures: The victims of the Orlando shooting Oscar A. Aracena-Montero An undated photo from the Facebook account of Oscar A. Aracena-Montero, who police identified as one of the victims of the shooting massacre that happened at the Pulse nightclub of Orlando, Florida, on June 12, 2016. Oscar Aracena via Facebook/Handout via REUTERS ATTENTION EDITORS - THIS IMAGE WAS PRIVIDED BY A THIRD PARTY. EDITORIAL USE ONLY. NO RESALES. NO ARCHIVE. REUTERS In pictures: The victims of the Orlando shooting Luis Daniel Wilson-Leon An undated photo from the Facebook account of Luis Daniel Wilson-Leon, who police identified as one of the victims of the shooting massacre that happened at the Pulse nightclub of Orlando, Florida, on June 12, 2016. Lestat Wilson via Facebook/Handout via REUTERS ATTENTION EDITORS - THIS IMAGE WAS PRIVIDED BY A THIRD PARTY. EDITORIAL USE ONLY. NO RESALES. NO ARCHIVE. REUTERS In pictures: The victims of the Orlando shooting Martin Benitez Torres An undated photo from the Facebook account of Martin Benitez Torres, who police identified as one of the victims of the shooting massacre that happened at the Pulse nightclub of Orlando, Florida, on June 12, 2016. Martin Benitez via Facebook/Handout via REUTERS ATTENTION EDITORS - THIS IMAGE WAS PRIVIDED BY A THIRD PARTY. EDITORIAL USE ONLY. NO RESALES. NO ARCHIVE. REUTERS In pictures: The victims of the Orlando shooting Stanley Almodovar Facebook/Stanley Manolo Almodovar III In pictures: The victims of the Orlando shooting Eddie Justice Faebook/ Eddie Justice In pictures: The victims of the Orlando shooting Luis Vielma Twitter/@jk_rowling In pictures: The victims of the Orlando shooting Eric Ivan Ortiz-Rivera Facebook/ Eric Rivera In pictures: The victims of the Orlando shooting Juan Ramon Guerrero Facebook/ Juan Ramon Guerrero In pictures: The victims of the Orlando shooting Peter O. Gonzalez-Cruz Facebook/ Peter Gonzalez Cruz In pictures: The victims of the Orlando shooting Amanda Alvear Facebook/ Amanda Alvear In pictures: The victims of the Orlando shooting Anthony Disla Facebook/ Anthony Disla In pictures: The victims of the Orlando shooting Edward Sotomayor Twitter/@ryanraiche In pictures: The victims of the Orlando shooting Luis Omar Ocasio-Capo Facebook/Luis Omar Ocasio-Capo In pictures: The victims of the Orlando shooting Kimberley Morris Twitter/ ‏@katiezavadski

And so to Donald Trump. His candidacy might at first have been a carnival show, notable for gargantuan rallies of fervent supporters, a vicious way with insults, and an ability to break every rule of politics and prosper. But there was another less remarked-upon aspect: the odour of violence that followed him on the campaign trail, and a fear among those who covered him that the passionate dislike he also inspired could see someone take a potshot at him.

Mercifully again, that hasn’t happened. But the atmosphere isn’t going to improve. Trump is now the presumptive Republican nominee (though I wouldn’t bet against a doomed attempt by ever more terrified party bosses to stop him at next month’s convention), and one thing is quite clear. He’s not going to get more house-trained and “presidential” as the general election draws near. For one thing he’s 70 – a bit old even in America for self-reinvention. And in Trump's own baseball metaphor, “If you’ve won the pennant [i.e. the primaries], why change for the World Series?”

But is this really so different from the fight over Brexit? Even the respective war cries on each side of the Atlantic mirror each other: “America First” in the case of Trump, “Britain First”, some claim, on the lips of the suspect in the Jo Cox case?

Clinton-Trump is set to be one of the nastiest presidential battles ever. However by Britain’s more sedate political standards, the Brexit referendum has been a pretty torrid affair, full of angry words, insults and apocalyptic warnings. Angry words have a way of producing angry deeds. If it was confirmed that Cox died because of her pro-Remain views and her work on behalf of refugees and immigrants, would that be so surprising?