Wikipedia[0] says this:

> Ferguson's research has raised questions by virologist Hendrik Streeck. Ferguson is the corresponding author for a paper titled "Impact of non-pharmaceutical interventions (NPIs) to reduce COVID-19 mortality and healthcare demand", which describes itself as having "informed policymaking in the UK and other countries in recent weeks".[55] Streeck stated in reference to the paper "In the – really good – model studies by the Imperial College about the progress of the epidemic, the authors assume, for example, that 50 percent of households in which there is a case do not comply with the voluntary quarantine. Where does such an assumption come from? I think we should establish more facts."[56] The computer models which Ferguson authored were initially criticised as "unreliable" and "a buggy mess,"[57][58] but subsequent efforts to reproduce the results were successful.[59]

[0] https://en.wikipedia.org/wiki/Neil_Ferguson_(epidemiologist)

[59] https://www.nature.com/articles/d41586-020-01685-y

What was wrong with the modelling though? Even after all we know now leaving the epidemic unchecked would easily triple our yearly mortality. Based on what we know now we'd still do lockdowns. Probably more severe and shorter ones sooner.