I must say that this did strike me as a little odd, but I am no henge expert. However, as the bank would have been made from the excavated earth from the ditch it seems very unlikely that the bank would have been that far from the fosse.

Here's what I think.....

You will either see this internal plateau bedecked with picnic tables and a hot dog stand

OR

They are planning to hold concerts and plays there and thus seat people around the edge inside and on the bank.

Just my initial cynical thoughts, you understand.

Did the archeaologist say there was evidence for such a huge area?