If it were not the real Stone in the first place, then why did the Scots go
to all the trouble of stealing it back in the first place?
Anyone who has ever "dowsed" Westminster Abbey can tell you there is a
significant power shift in the area of the Coronation Chair. I've heard it's
over a dry well which may explain it in terms of leylines and vortices, but
there's something there.
Sistank is probably Cesstank, as in Cesspool. Sounds to me to either confirm
the dry well story or be merely a disparaging remark about the British
Monarchy, which sounds about right for some of the more vehement feelings of
certain Scottish Nationalists.