The 1975 topped the bill at Leeds Festival, replacing Rage Against the Machine.
It is after second headliner Halsey soldiered on through sickness.
Matty Healy's group stepped in at two weeks' notice, sparking much debate, due to Zack De La Rocha's leg injury.
Earlier Halsey had to take a break mid-track.
It's revealing she had been suffering all day with a bout of food poisoning.
She powered through her set and covered Kate Bush's resurgent Running Up That Hill (A Deal with God).