The Fallen Sign

I was traveling from Chesterton to Newcastle recently when I came across a sign which had fallen off its post at the crossroads. It was marked to Newcastle, Chesterton, Knutton and Silverdale. Unfortunately I didn't know which road to take to Newcastle and had hoped the sign would help. Luckily, I had a great idea which helped me put the sign back up pointing correctly to Newcastle. What was my idea? I simply pointed Chesterton back the way I had come and this left the sign in its correct orientation.