Singer-songwriter will release follow up to 2008's 'Modern Guilt' next year
The single is the third stand-alone track to be released by the singer this year
The 'Butter Edition' of 'Key To The Kuffs' also includes an appearance from Clams Casino
The alternate version of the stand-alone single features a spoken word vocal from the former Sonic Youth member
Beth Orton, Charlotte Gainsbourg and The Mighty Boosh also performed
US musician follows up 'Defriended' with another new track
Cambridge and London shows confirmed by US singer
The song will not feature on either of his two upcoming albums
The singer-songwriter played 'Sorry' and 'Heaven's Ladder' last night in Santa Cruz, California
Charlotte Gainsbourg and Michael Kiwanuka also among artists involved in unique gig