Could they possibly go to East Midlands Railways, and achieve 12 cars on the Corby to London St Pancras service , or be used between Market Harborough and London St Pancras on the newly electrified extension, and possibly extended to Leicester on battery, for capacity and service improvements, as to provide extra services, so some more services can run non stop, from Leicester to London St Pancras. Especially those from Sheffield and Nottingham.
Don't they have enough 360s to run 12s? No way that the current service eats up that many diagrams.
This was an interesting idea, however for any MML service proposals, the question is whether this would be in addition to current 4x EMR IC, 2xConnect services per hour, or instead of.
"Instead of": I think it'd be politically and commercially unacceptable to sacrifice Nottingham and/or Sheffield IC services to instead run Connect-style services to Harborough or Leicester.
"in addition to": All options fall foul of the fact that the railway is full, particularly south of Harpenden.
However, only 3 out of 18 planned EMR departures from St Pancras between 1600 and 1900 today will be >200m long; most are ~125m 222 and ~160m 360.
So the way to add capacity - if it is really needed - is not more trains, but to increase train lengths to 240m.
As Class 466 noted, 350s aren't needed to get Connect services to 240m, there ought to be enough 360s
Unless they're comprehensively refurbished with >100km battery range, they are unsuitable for IC services, and if there was a burning need to add even more IC capacity, extending the 810 order seems like the way to go.