Inaccessible castle

We are not known for authentically old castles in Staffordshire (though Tutbury has some special ruins).  Which is why it's a shame that the ruins of the imposing thirteenth-century Chartley Castle are not accessible to the public.
I had to take this photo on a zoom lens to avoid trespassing.

The castle is most famous for being one of the prisons of Mary Queen of Scots.