The reasons behind terrorist attacks in Great Britain are many. During the 20th century, most attacks were carried out by various Irish Republican Army (IRA) groups and were linked to the Northern Ireland conflict (the Troubles). In the late 20th century there were also isolated attacks by Middle Eastern terrorist groups, though the vast majority of the attacks were the work of the IRA and splinter groups. During the 21st century, however, most terrorist incidents in Britain have been linked to Islamic fundamentalism. Since 1970, there have been at least 3,395 terrorist-related deaths in the UK, the highest in western Europe. The vast majority of the deaths were linked to the Northern Ireland conflict and happened in Northern Ireland. Between 1971 and 2001, there were 430 terrorist-related deaths in Great Britain. Of these, 125 deaths were linked to the Northern Ireland conflict, and 305 deaths were linked to other causes – most of the latter deaths occurred in the Lockerbie bombing.

Great Britain

19th century

1912–1914

From 1912 to 1914 the female enfranchisement movement, the suffragettes, orchestrated a bombing and arson campaign which was described by the suffragettes themselves as terrorism. Emmeline Pankhurst said the suffragettes committed these acts to "terrorise the British public" and the Women's Social and Political Union reported their own acts as a "Reign of terror". The campaign included burning down the houses of members of the cabinet, an axe being thrown at the Prime minister, attempted bombings of train stations including with nail bombs, and attempts to flood towns by attacking water courses. C.J. Bearman asserts that there were at least 337 arson or bombing attempts and that the cost of the campaign in 2021 money amounted to 140-240 million pounds. 1300 people had been arrested and imprisoned by the end of the campaign.

1939–1940

From January 1939 to March 1940, the Irish Republican Army (IRA) carried out a campaign of bombing and sabotage against the civil, economic, and military infrastructure of Britain. It was known as the S-Plan or Sabotage Campaign. During the campaign, the IRA carried out almost 300 attacks and acts of sabotage in Britain, killing seven people and injuring 96. Most of the casualties occurred in the Coventry bombing on 25 August 1939.

1970s

1980s

1990s

2000s

2010s

2020s

Prevented, failed or aborted attacks

These are known attacks which could have constituted a threat to life had they worked or been large enough. The list does not include attacks that were only at the planning stage, but were not actually in operation. Given the nature of counter-terrorism, successes in preventing terrorist attacks in the UK will not always come to light, or not be as heavily promoted as intelligence failures. However, during the police advocacy of 90-day detention in relation to the Terrorism Act 2006 they produced documents listing all the cases about which they could not go into details. Authorities often state, without going into details, numbers of attacks prevented, e.g. 12 attacks were reported in March 2017 to have been thwarted in the previous year, some only hours before they were to have been attempted.

Arrests, detentions, and other incidents related to the Terrorism Acts

These are cases where either the Terrorism Acts were invoked, or which the authorities alleged were terrorist in nature at the time. This list includes both plots that were foiled at an early stage before any materials were actually assembled, and totally innocent suspects.