Meseryrail's new trains will be able to switch from third rail (as one of the only networks to still use one), battery (about 20 mile range) and a pantograph.
Network Rail will not allow any new third rail lines so this is why they've done this.
They will be making the switch while on the line. For example a potential Liverpool to Preston line. They'll run on the third rail all the way to Ormskirk, before switching to battery to get to the Penwortham triangle where they can extend the pantograph, using them to power all the way into Preston while also charging the battery. Before doing the opposite on the way back out.
Northern Rail should be running to the bank to buy these hybrid trains.