First and foremost, I would like to express my sincerest gratitude to my supervisor, Professor M. M. Woolfson, for his continued support and encouragement during my time at York, especially for his patience towards an inquisitive mind.
Secondly, I would like to thank Yann Golanski, for the many hours we have spent discussing, arguing, understanding, and generally banging our heads together over all aspects of this thesis, especially with regards to SPH.
Aside from acknowledging the many friends that have made my time at York pleasurable, I would especially like to thank Alan, Geoff, Ian, James, Kin, Nige, Rob B, Rob K, Stephen and Tom, for the many fruitful discussions relating to this thesis.
Finally, I would like to thank all of my friends and family outside of York, for being there.