Core: Turning left: the wide arc, and three exceptions to 'left-past-left'

Before turning left you look in a fixed order: interior mirror, left door mirror, look aside to the left, and only once you know you can turn safely do you signal and smoothly move into position for the left turn (Book p.138). Here you give way to both straight-ahead traffic and oncoming traffic turning right. Take the turn wide, so that you land on the right-hand side of the road you are entering — and don't cut the corner (Book p.138). Two oncoming drivers who both want to turn left normally pass 'left-past-left'. This has three named exceptions: the oncoming driver has already clearly committed to a different way of turning, road markings indicate otherwise, or there is a wide central reservation (Book p.139). Finally: watch for traffic coming up behind you, both before you move into position and again right before you actually turn (Book p.138) — turning left therefore requires checking in two directions at once, forward and behind.