Viewing figures for the prime minister’s pre-recorded address surpassed major events such as the news coverage of John F Kennedy's assassination, the 1969 moon landing and the finale of the 2012 Olympics.
The figures do not take into account audiences on internet livestreams such as YouTube and Amazon Prime.
It means the true viewing numbers for the six-minute broadcast could even overtake Princess Diana’s wedding (28.4 million) and funeral (32.1 million) and even the 1966 World Cup final (32.3 million).
The most recent events to attract large audiences were the opening and closing ceremonies of the 2012 London Olympics, which both seen by more than 24 million people. An estimated 16 million people in the UK tuned into the Apollo 13 mission, although figures from the 1960s and 1970s, when there were fewer channels, are believed to be less accurate than those for more recent years.
Mr Johnson’s announcement was also more widely viewed than other major TV moments such as Hilda Ogden’s departure from Coronation Street and the 1996 Only Fools and Horses Christmas special.
The most-watched TV programme, excluding news and sport events, remains the 1986 Eastenders Christmas Day episode seen by 30.1 million people.
During his address, the prime minister told the nation “you must stay at home” and announced the closure of most shops, public buildings and leisure facilities.
He banned gatherings of gatherings of more than two people unless they were members of the same household or it was essential for their work.
Under new legislation expected to come into force later this week, police will have powers to “disperse” groups and issue fines to anyone flouting the lockdown.
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