400mm metre trains are common in Europe and indeed at St Pancras . There is no engineering problem for two Pendolino’s to operate safely , the limitations are rather short platforms lengths encountered at many stations along the West Coast route. Manchester Piccadilly platform 9 would and has accommodated 18 car trains in the past , Euston can on several platforms, Crewe and New Street could as well. The general reason other than breakdown rescues it don’t happen is the schedules don’t work for what would likely be a down route train splitting operation on scale. Now contrarily the SNCF/ En Oui TGV services across the waters routinely down route split. Now having said the Voyagers and soon those Hitachi models are designed to allow down routes spitting modes to be included albeit in smaller consists.
