Hands up if like me, you didn't see Reading - Southampton conversion coming?
I don't know if it is sensible or even possible to run third rail DC and 25KV overhead at the same time for any prolonged period. At some point SWT will need a new sub-fleet of Class 444 and Class 450 created that will be able to operate on dual-voltage.
Should be easy enough, all they need to do in preparation is send the 444s and 450s for a refurb/refit 1 at a time while the OHLE is being installed, then apart from the 455s and 458s, they have a fleet of go-anywhere electrics.
I'm presuming that Southampton - Weymouth and various other parts of 3rd rail land will be converted in CP6.
However, with today's announcement, I still feel the DfT have missed a trick in excluding Birmingham - Derby and various lines around Sheffield from CP5 electrification schemes. The potential is there for a lot of services to be converted to EMU operation, but will have to stay DMU operated as the OHLE will be dis-jointed. For example. Newcastle - Reading/Southampton. The majority of the route will be under wires soon, apart from Doncaster - Sheffield and Derby - Birmingham.
While the big announcement today was a very good one for the railway in general, I don't think it has been that well thought out. The various schemes seem to have been picked out of a hat at random, and apart from the MML, don't make that much sense when looked at individually.