This document discusses using demand-side options like smart loads to improve stability in autonomous power systems. It aims to investigate the availability of fast short-term power reserve from loads to aid voltage regulation and frequency control. The researcher aims to estimate the total reserve from suitable industrial and service sector loads in Great Britain. Simulation results show that smart loads can provide effective rapid frequency response to arrest frequency dips and improve rate of change of frequency after a large loss of power infeed. Estimates find over 1.76 GW of reserve potential from smart loads and 0.87 GW from motor loads.