Stan’s wife used to drive him to the train station and then he'd take the train and go to work. At the end of the day, he'd get on the train to come home. When he arrived back at the train station, his wife would meet him there precisely when he got off the train and they'd drive home together.
One day Stan decides to leave work early an hour early. Needless to say, he gets to the train station an hour early. Rather than call his wife, it's a nice day and he decides to hoof it. So he starts walking in the direction she'll be driving. And low and behold, he sees his wife coming up the road and she sees him by the side of the road. He gets in the car and they drive home and arrive 20 minutes earlier than usual even though she left home at the usual time since she didn’t know he was going to leave work early.
How long was he walking before they met?