The xx04 departure would get it neatly to Cambridge on time to pick up the current xx30 Stansted departure path (and would also flight behind the xx57 Lime Street and xx00 Liverpool street departures from Norwich, before stopping its way to Ely)
But that shafts the possibility of people from intermediate stations like Attleborough getting to Peterborough and the world beyond there.
Presently, the Cambridge train preceeds the EMT service, so you can change at eg Thetford or Ely to pick up the EMT. The reverse is true coming back to Norwich. It works quite well.