Welsh centre Jamie Roberts - facing Australia for the first time this summer due to injury - has scored the Lions' fourth try, taking a pass from replacement Conor Murray before galloping home.
Halfpenny makes it another seven points, and the Lions start to celebrate a series win.
More top news
A mild and murky night with rain clearing but fog patches gathering by the early hours of the morning.
Police are appealing for information after a man died following an assault outside a hospital.
Joyce Cox's body was found in woodland in Cardiff just after the outbreak of World War Two.