I think what he meant was that if we had locked down earlier when there were only small death numbers people would be complaining how unnecessary it was and would have flouted the guidelines which ultimately would have resulted in far more deaths in the longrun
We didn't need to lockdown fully - but we could easily have introduced restrictions on gatherings, large events etc much earlier than we did.
We went from school closures, pubs closures to this lockdown over 4 days.
On 2 March, Boris Johnson said in an interview with BBC News: "The most important thing now is that we prepare against a possible very significant expansion of coronavirus in the UK population
On 18 March, MP Lloyd Russell-Moyle announced that he had tested positive for with the virus.[545] Boris Johnson made a statement on his daily briefing, announcing that all schools in the UK were to close on Friday to everyone except those who have parents with important jobs that they can't do from hom
On 20 March, Prime Minister Boris Johnson requested the closure of pubs, restaurants, gyms, entertainment venues, museums and galleries that evening, though with some regret saying "We’re taking away the ancient, inalienable right of free-born people of the United Kingdom to go to the pub
On 23 March, Boris Johnson announced in a television broadcast that measures to mitigate the virus were to be tightened further in order to protect the NHS, with wide-ranging restrictions made on freedom of movement, enforceable in law,[22] for a "stay at home" period which would last for at least three weeks. Johnson did not use the word "lockdown" in his broadcast but the term was widely adopted in media