  We discuss first a method of measuring $\tau$ polarisation at the ILC using
the 1--prong hadronic decays of the $\tau$. We then show in this contribution
how a study of the $\tilde \tau$ sector and particularly use of decay $\tau$
polarisation can offer a very good handle for distinguishing between mSUGRA and
a SUSY-GUT scenario, both of which can give rise to appropriate Dark Matter.
