Indeed, the east-west orientation of graves is a very old custom. It's often found that there is a transition from random orientation of graves (often focused on, say, a barrow) to east-west orientation in ancient cemeteries, and archaeologists use it as a way of assessing the Christianisation of ancient communities. Here's an example (from Whitby Abbey).

There is often a 'twist' in old English churches, the nave being slightly out of alignment with the chancel. This is often suggested to represent the attitude of Jesus on the cross. Others think it might be simply due to the fact that the priest was responsible for the chancel, but the people of the parish for the nave, and perhaps they couldn't agree which way was exactly east.