The Beady Eye frontman squared up to the 'The Wire' star at London's Ivy Club following the NME Awards in February and pulled Idris' red bobble hat off his head, and Liam has now opened up about the real reason behind the altercation for the first time - the actor had ruffled his perfectly coiffed hairdo.
He told British station Absolute Radio: ''I didn't steal Idris' hat, or grab it. I don't go grabbing anyone. He messed my f***ing hair up, so I pulled his hat off and booted it across the room, and that's it.''
Reports at the time claimed Idris - who was accompanied by his 'Luther' co-star and former World Thai boxing champion Warren Brown at the bash - was in a good mood and let it drop without things getting physical.
However, infamous wildman Liam sees things differently, insisting he had every right to go ballistic because you should never mess with someone's haircut.
The 'Flick of the Finger' singer ranted: ''I don't give a f**k. I didn't know who he was. I still don't know who he is and I don't give a f**k who he is.
''You don't touch a man's haircut, man, especially if you've got a red bobble hat on. So let's get that one straight. He f***ed up my hair - so the hat got it.''
The former Oasis star and his Beady Eye bandmates played a special acoustic set for Absolute Radio at the world famous Abbey Road Studios on Monday night (03.06.13).
The group - also comprised of Gem Archer, Andy Bell, Chris Sharrock and Jay Mehler - played tracks from their new album 'BE', including 'Second Bite of the Apple', 'Ballroom Figured', 'Don't Brother Me' and 'Iz Rite'.
They also performed a cover of The Beatles' 'Cry Baby Cry' in Studio 3 - which is synonymous with The Fab Four.
Listen to Beady Eye's gig in full on Pete Donaldson's evening show on Thursday (06.06.13) from 9pm on Absolute Radio and watch Liam's interview at www.absoluteradio.co.uk/video.