As someone has posted them on Facebook - here are the registrations for the new vehicles:
ADL E400
7534 NK15ACF
7535 NK15ACJ
7536 NK15ACO
7537 NK15DZO
7538 NK15DZP
7539 NK15DZR
7540 NK15DZS
Wright Streetlite
Darlington (MAX X1)
1590 NK15AAE
1591 NK15AAF
1592 NK15AAJ
1593 NK15AAN
1594 NK15AAO
Durham (Sapphire 22)
1595 NK15AAU
1596 NK15AAV
1597 NK15AAX
1598 NK15AAY
1599 NK15AAZ
1600 NK15ABX
1601 NK15ABZ
RE: Arriva North East: Latest News & Discussion - March 2015