  The chiral p-wave superconducting state is comprised of spin triplet Cooper
pairs carrying a finite orbital angular momentum. For the case of a periodic
lattice, calculating the net magnetisation arising from this orbital component
presents a challenge as the circulation operator $\hat{\bf{r}} \times
\hat{\bf{p}}$ is not well defined in the Bloch representation. This difficulty
has been overcome in the normal state, for which a modern theory is firmly
established. Here, we derive the extension of this normal state approach,
generating a theory which is valid for a general superconducting state, and go
on to perform model calculations for a chiral p-wave state in Sr$_2$RuO$_4$.
The results suggest that the magnitude of the elusive edge current in
Sr$_2$RuO$_4$ is finite, but lies below experimental resolution. This provides
a possible solution to the long-standing controversy concerning the gap
symmetry of the superconducting state in this material.
