The So Here We Are rockers went their separate ways in June, 2013 after a final performance at Britain's Latitude Festival without their drummer Matt Tong.
After announcing they were ending the hiatus to work on a new record in March (15), the band returned to performing in August (15) without Tong and bassist Gordon Moakes at an intimate gig in California.
Now, the band's frontman Okereke has admitted there was more to the hiatus than a desire to work on solo projects, revealing tensions over drug use contributed to the split.
"I can tell you it was about someone doing cocaine and someone not being into it. That's all I'm gonna say," Okereke tells Britain's NME magazine. "People think bands breaking up is sexy but often it's super mundane, like not flushing the toilet or washing up. It's often not about the flashpoints but deep-seated issues."
Tong has been replaced by Louise Bartle on drums and Moakes by Justin Harris on bass alongside Okereke and guitarist Russell Lissack in the new line-up.
At the time of the split, Lissack admitted that internal tensions on their previous tour had played a part in the band's decision to take time off.
"Maybe we'll play an amazing show and we'll be on a real high and then the next day some minor thing will happen and everyone hates each other," the musician told Canadian newspaper the National Post.
Speaking in 2007, before the band first took a break from 2009 to 2012, Okereke admitted occasionally trying illegal substances, but stated that he preferred the drug ecstasy to cocaine.
"Cocaine can be very attractive, very seductive. But for me, it's bad news because that drug can really damage your voice," Okereke told British magazine Uncut. "The drug I do enjoy taking is ecstasy, which gives a real sense of euphoria. It makes your senses so much more acute. It makes music sound so powerful. And it makes touch incredibly sensual. You know, every touch is orgasmic.
"These days I don't even bother with pills that often. To be honest, I haven't taken anything for a whole year."