On 8 June 1968, James Earl Ray, the man convicted of the assassination of Martin Luther King, Jr., was captured and arrested at Heathrow Airport while attempting to leave the United Kingdom on a false Canadian passport. On 19 May 1974, the IRA planted a series of bombs in the Terminal 1 car park. Two people were injured by the explosions.
On 26 November 1983, the Brink's-MAT robbery occurred, in which 6,800 gold bars worth nearly £26 million were taken from a vault near Heathrow. Only a fraction of the gold was ever recovered, and only two men were convicted of the crime.
On 17 April 1986, semtex explosives were found in the bag of a pregnant Irishwoman attempting to board an El Al flight. The explosives had been given to her by her Jordanian boyfriend and father of their unborn child Nizar Hindawi. The incident became known as the Hindawi Affair.
On 21 December 1988, Pan Am Flight 103 from Heathrow to New York/JFK was blown up over Lockerbie, Scotland, killing all 259 on board and 11 other people on the ground.
In 1994, over a six-day period, Heathrow was targeted three times (8, 10, and 13 March) by the IRA, who fired 12 mortars. Heathrow was a symbolic target due to its importance to the UK economy, and much disruption was caused when areas of the airport were closed over the period. The gravity of the incident was heightened by the fact that the Queen was being flown back to Heathrow by the RAF on 10 March.
In March 2002, thieves stole US$3 million that had arrived on a South African Airways flight. In February 2003, the British Army was deployed to Heathrow, along with 1,000 police officers, in response to intelligence reports suggesting that al-Qaeda terrorists might launch surface-to-air missile attacks at British or American airliners. On 17 May 2004, Scotland Yard's Flying Squad foiled an attempt by seven men to steal £40 million in gold bullion and a similar quantity of cash from the Swissport warehouse at Heathrow. On 10 August 2006, the airport became the focus of changes in security protocol, following the revelation of a supposed al-Qaeda terrorist plot. New security rules were put in force immediately, causing additional but essential[citation needed] restrictions in regards to carrying liquids on board flights. This caused longer queues and wait times at security. These included the prohibition of carry-on luggage (except essential items such as travel documents and medication) and all liquids – although this rule was later relaxed to allow the carrying on board of liquid medications and baby milk, provided that they were tasted first by passengers at the security checkpoint. On 25 February 2008, Greenpeace activists protesting against the planned third runway managed to cross the tarmac and climb on top of a British Airways Airbus A320, which had just arrived from Manchester Airport. At about 09:45 GMT the protesters unveiled a banner, saying "Climate Emergency – No Third Runway", over the aircraft's tailfin. By 11:00 GMT four arrests had been made.On 13 March 2008, a man with a rucksack scaled the perimeter fence onto runway 27R, and ran across the grounds, resulting in his subsequent arrest. A controlled explosion of his bag took place, although nothing suspicious was found, and the Metropolitan Police later said that the incident had not been terrorism related.