Frontman Luke Spiller recalled to HMV
that the song originated in the summer of 2019 when The Struts were on tour. While his bandmates were at the bar, Spiller was in the tour bus playing around with his guitar. He came up an idea for the chorus and verse for "Strange Days," which he recorded into his phone as a voice memo.
Nine months or so later, in the early days of lockdown, The Struts launched their Quarantine Radio Instagram Live
show. Robbie Williams hit up Spiller out of the blue during the show and they ended up FaceTiming for a couple of hours. They got on really well and The Struts frontman asked Williams if he would be interested in laying down some vocals if an appropriate song came up.
A fortnight later, The Struts moved into the Los Angeles home of their producer, Jon Levine, to record their third album. After completing about eight of the songs, Spiller listened back to the "Strange Days" voice memo and recognized it had "that old school Robbie Williams, Britpop vibe to it." Levine liked the idea, but they realized they needed more lyrics, so Spiller started scatting and throwing in lines from a couple of different song ideas he'd had.
Two weeks later, Williams invited Spiller over to his Beverly Hills home and the pop star laid down his vocal on his front porch.