I am skeptical about the new variant in NE although, of course, this needs to be checked and, hopefully, ruled out.
When Alpha first appeared in the UK, the growth initially started in Swale and Thanet and spread out to surrounding areas.
The rise of cases in NE occurred across a number of local authorities at the same time. Christina Pagel picked up on Newcastle but the fastest growing borough was in fact South Tyneside. It is still going up leading the growth across the rest of the region.
It is possible that the new variant was quickly seeded across NE but I will be surprised if it indeed turns out to be the case. For now I still believe the Warwick prediction (the highest wave in NE given relatively low acquired immunity from the winter wave) is a most likely explanation.