When , at the December 1969 IRA convention and the January 1970 Sinn Féin Ard Fheis the delegates voted to participate in the Dublin ( Leinster House ) , Belfast ( Stormont ) and London ( Westminster ) parliaments , the organisations split .
At the December 1969 IRA convention and the January 1970 Sinn Féin Ard Fheis ( the Irish words for a party conference or convetion ) the delegates voted to participate in the Dublin ( Leinster House ) , Belfast ( Stormont ) and London ( Westminster ) parliaments , the organisations split into Provisional and Official parts .