There's still not much details- interesting that that report seems to suggest that the Hertford East services (which are mainly via Tottenham hale) and Stratford-Stortford will remain with the franchise perating to Stansted and Cambridge- though this somewhat makes sense as those are mainly operated by the same units as Cambridge services- though 317s also operate to Chingford. Some complex diagramming ahead with this split- may require the off-lease 317/7s back in action