Lean premixed combustion is widely used for gas turbines in the power generation industry, these conditions decrease NOx production through a reduction in flame temperature and potential for local hot spots. However, these conditions are also susceptible to instabilities, in literature the mechanisms of these instabilities have been investigated through physical experiments, numerical investigations and simulations. This thesis reviews the instability mechanisms and identifies the mixing quality as a key area for further development using traditional and novel diagnostic techniques to measure temporal and spatial velocity and concentration variations.