...At first glance it looks like the avenue finished at the Cove...
Depends how you look at it though doesn't it? This past week they've also failed to find what we know was the "middle bit" of the West Kennett Avenue. Maybe that's all that's happened at Beckhampton?
Pete, if a stone was big enough, and the right shape, could it just have been placed, without a hole? Would the evidence show up?