The old solution was poor, before the first big timetable change on National Express East Anglia you had two EMU's from Ipswich and two locl hauled sets from Norwich to London which was a bit overkill, admittedly.
But killing both of those two EMUs and running a 2 or 3 car 170 through the branch lines to Liverpool Street was a dreadful waste of a path and often dreadfully overcrowded.If such services come back it should be on the basis that it's either the fourth train per hour through Ipswich, or it replaces the current EMU service through Ipswich, but runs in multiple with another unit.