The Bichard Inquiry, launched in 2003 following the Soham murders, exposed failures in police vetting and intelligence-sharing, leading to crucial reforms in child protection. Its 2004 report resulted in the creation of the Disclosure and Barring Service (DBS) to ensure stricter background checks for individuals working with vulnerable groups.

On 7 July 2005, four suicide bombers detonated explosives on three London Underground trains and a double-decker bus, killing 52 people and injuring nearly 800 in the worst terrorist attack in British history since Lockerbie 1988. The bombers, linked to Islamist extremism, carried out coordinated strikes during morning rush hour, causing chaos across London and prompting an extensive investigation into security failures and counterterrorism strategies. The attacks led to major reforms in UK security policy, including enhanced intelligence-sharing, increased surveillance, and stricter anti-terrorism laws.

On March 22, 2017, Khalid Masood drove a car into pedestrians on Westminster Bridge, injuring over 50 people and killing four before crashing into the perimeter fence of the Palace of Westminster. He then ran into New Palace Yard, where he fatally stabbed an unarmed police officer before being shot dead by armed officers. The attack was treated as Islamist-related terrorism, though UK authorities found no direct links between Masood and any terrorist organization.

The Daniel Morgan Independent Panel was an eight-year investigation into the unsolved 1987 murder of Daniel Morgan, exposing institutional corruption within the Metropolitan Police and making 24 recommendations to improve accountability, transparency, and support for victims' families.

The Statutory Inquiry into the Death of Jalal Uddin investigates the circumstances of his 2016 murder, focusing on systemic issues, counter-terrorism measures, and police actions, aiming to provide recommendations to prevent similar tragedies.

The Dawn Sturgess Inquiry is an independent investigation into the circumstances surrounding the 2018 Novichok poisoning incident in Salisbury, focusing on the death of Dawn Sturgess.

The Dunblane inquiry investigated the tragic shootings at Dunblane Primary School, resulting in recommendations to improve firearm control and school security

The Rosemary Nelson Inquiry investigated the circumstances surrounding the murder of solicitor Rosemary Nelson and examined potential collusion between state agencies and paramilitaries

The Litvinenko Inquiry was a public investigation chaired by Sir Robert Owen, examining the circumstances surrounding the death of Alexander Litvinenko, who was poisoned with polonium-210, and concluded that the Russian state was likely involved