A video on Facebook claims to show an air raid siren playing in central London. The video has been viewed over 23,000 times.
The video shows a number of people running along Park Lane at night and appears to have been filmed in November or December given the presence of the Winter Wonderland ferris wheel. We cannot tell which year the video dates from, nor why some people in the clip appear to be running in apparent panic.
However, it is highly unlikely that the air raid siren playing throughout the clip is genuine. Firstly the civilian alert system that claims to be shown in the video—a public siren—largely does not exist in the UK anymore. By 1992, following the end of the Cold War, the civil defence siren was retired, and some of the sirens repurposed as flood or hazardous chemical warnings. However, even these are now being slowly replaced with newer technologies like text alerts.
According to the Cabinet Office, modern warning systems consist of a multi-channel approach, including broadcast and social media.
Because of the rarity of the siren systems, it would have been notable for one to have played in London. We could find no reporting of a siren having sounded in the area around Park Lane and Hyde Park in recent years, but there was coverage when sirens sounded in Greenwich following a fire in 2012, or during WWII commemorations in the City of London in 2015.