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.
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The tree was blown down in a gale in February after standing for more than 200 years.
Aberdaron recorded wind speeds of 70mph this morning. A warning is issued covering the whole of Wales.
Ospreys prop Nicky Smith is the only uncapped player named in the party.