  The rare Hyperon decay $\Sigma^+ \to p \ell^+ \ell^-$ is an $s \to d$ flavour
changing neutral current, and is therefore suppressed in within the Standard
Model, making it an excellent probe for new physics. The process is dominated
by long distance processes and therefore lattice QCD is the only existing
technique to obtain a first principles Standard Model theoretical prediction.
We present our work on an unphysical exploratory study of the rare Hyperon
decay on the lattice, including an investigation into the applicability of
source-sink sampling for this decay, and we show a generalisation of the summed
method for arbitrary 3-point functions and 4-point functions. In addition we
show preliminary results for a computation of the $s \to u$ semileptonic
Hyperon decays.
