cont...
In light of your earlier post regarding this. Generally it doesn't matter if you have an MA, MSc, MChem, MEng these wouldn't bypass the initial MPhil period of a PhD in the UK. The replies on that thread did answer your question but here you go. You seem to want to be able to label the MPhil as a seperate entity from the PhD, and so for this reason consider the MPhil the period where you prove yourself capable of working on your own and planning experiments, and have a chance to develop your research skills, learn new techniques and research your specific thesis area to enable you to complete the PhD.. something that a taught masters program would not necessarily cover.