When Liam did just that, auditioning with another classic song, Cry Me A River, in 2010, the missing pieces were all now in place.
As he started singing, Cowell’s eyes lit up as he registered Liam’s newfound maturity and charisma.
Whatever the X factor is, Liam had it.
The judges still faced a tough decision that year – so during a discussion about whom to save, they decided they could keep five boys by putting them together in a group.
Liam, Zayn Malik, Louis Tomlinson, Niall Horan and Harry Styles were informed they were now a boy band – and One Direction were born.
They didn’t actually win The X Factor that year, coming third behind Matt Cardle and Rebecca Ferguson in a final watched by 17 million people.
But Cowell knew a good thing when he saw it. He signed them to his label and, after waiting nine months to release their debut single, they soon outpaced their rivals.