I have yet to see in this forum or in the goverment's plans any justification for the electrification of the MML. The enormous capital costs will take take decades to repay at today's rates, if at all, as there are no hard figures on running costs of the vehicles involved. As far as journey times are concerned there is not going to be much of a saving on London-Leicester as this town has virtually the same average speeds on journeys as London-Birmingham, which is already electrified. I will concede that London-Sheffield could gain on speed but this would appear not to be a power issue that electric traction could improve but a track constraint. Electrification is not the answer to this, track alignment probably is. PS current average speeds from London to Leicester are 87mph, Derby 85mph and Sheffield 77mph. Hardly slow, consider the following London to Three Bridges (where I live) 52mph, London to Brighton 56mph.
How about this, if 25kV electrification is so beneficial then why not electrify the whole of the network South of London and make mega savings as the traffic density is magnitudes greater than any of the proposed electrified routes.