Tags: Northern Ireland DUP leader Jeffrey Donaldson resigns, DUP leader Sir Jeffrey Donaldson resigns, DUP leader, DUP leader Jeffrey Donaldson resigns, Leader, 'historic, Sir Jeffrey Donaldson, Northern Ireland, allegations, offence charges, offences, sex offence charges, unionist party steps, Leader Jeffrey Donaldson Resigns, D.U.P, police charges,