Livingston booked their place in the next round of William Hill Scottish Cup with a routine 3-1 win at Peterhead.The Ladbrokes Championship side needed only 14 minutes to go ahead as Gary Glen fired home from close range.And that gave them the platform to go on and dominate as they doubled the lead in the 25th minute when Jordan White coolly slotted home from Liam Buchanan.It was White that made absolutely sure with his second from close range with 16 minutes remaining before Peterhead finally gave their supporters something to cheer when Rory McAllister struck a stoppage-time penalty.