On Tuesday, a Sudanese immigrant to the United Kingdom named Salih Khater crashed his car into cyclists and pedestrians in a terrorist attack in London. Fortunately, Khater did not murder anybody in his attack but he did injure three pedestrians, one of whom was so lightly wounded that he was treated at the scene and released. The other two wounded people have since been released from the hospital. 

Terrorism has been relatively common in the United Kingdom for decades, from the Irish Republican Army to al Qaeda to ISIS. However, there is little research on the actual risk of a British person being killed or injured in a terrorist attack. This post is an attempt to quantify that risk.

According to data from the Global Terrorism Database at the University of Maryland, the RAND Corporation, and online sources for 2018, terrorists murdered 2,402 people in the United Kingdom from 1975 through August 14, 2018 (Figure 1). Despite increases in the number of murders committed by terrorists in recent years, especially a series of horrible attacks in 2017 that murdered 42 people, the long run trend is a decline in the number of people murdered by terrorists in the United Kingdom. Figure 2 shows that 5,267 people were wounded in terrorist attacks in the United Kingdom during the same period. Figures 1 and 2 only include victims and exclude the terrorists themselves from the death and injury statistics. Using existing data sources, somebody with knowledge and a lot of time could use the GTD and RAND databases to identify the nativity, ideology, and other characteristics of each terrorist like I did for the United States. 

From 1975 through August 15, 2018, a British person’s chance of being murdered in a terrorist attack on British soil was about 1 in 1.1 million per year. But that annual chance of being murdered in a terrorist attack obscures big shifts over time. Over the last decade, the annual chance of being murdered in a terrorist attack on British soil was about 1 in 11.4 million per year, far lower than the entire 1975–2018 period. Especially relevant is the number of injuries given that Khater only injured people in his attack. The annual chance of being injured over the entire time was 1 in 496,464 per year, but only 1 in 1.4 million per year over the last decade. 

Figure 3 tries to show how the risk has changed over time by using a moving three-year average of the annual chance of being murdered in a terrorist attack. I used a three-year moving average because zero people were killed by terrorists in many years and one cannot divide by zero. A note about reading Figures 3 and 4: the Y‑axis is the annual chance of being murdered or injured in a terrorist attack, so the 2011 number of 63,280,444 in Figure 3 means that the chance of a British person being murdered in a terrorist attack was 1 in 63,280,444 that year. Thus, the higher the number, the lower the chance of being murdered in a terrorist attack. 

Figure 3 shows that the annual chance of being murdered in a terrorist attack fell rapidly from 1975 through 2004, rose over the next several years, fell again, and has been increasing since about 2012. Dropping the moving gives sharper divides: In 2016, 2017, and 2018 (so far), the annual chance of being murdered in a terrorist attack was about 1 in 7.3 million per year, 1 in 1.8 million per year, and zero (so far), respectively. 

Figure 4 shows a similar decline in injuries inflicted by terrorists from 1975 through 2003 that abruptly reverses in 2004, falls again in the following years, and then starts to increase over the last few years. 

These above figures show that the chance of dying or being injured in a terrorist attack in the United Kingdom is small. Yet terrorism succeeds in terrifying people. None of the numbers above would give comfort to the actual victims of terrorism or their families because what happened to them is the equivalent of “winning” an evil anti-lottery. But the above numbers should show British citizens, their government, and the world at large that terrorism is a relatively small problem in the United Kingdom.