Preliminary counts have Allan with a 4646-vote lead over Tapsell and the race is won.
Much like Ilam has been taken from Gerry Brownlee and Hamilton East from David Bennett, the electorate has flipped the script for what it means to be a safe seat.
The nationwide shift towards Labour has played out in the East Coast - a blue seat since 2005.
There was disappointment in the air at Tapsell's election wrap party and while no candidate takes their election for granted, I wondered if the National Party thought their seat was safe.
It was a fleeting thought, however. You need only look at the campaign Tapsell ran to see she put her all in to win the seat.
As the East Coast is the largest electorate in the North Island, Tapsell travelled 17,000km on the campaign trail, she says.
And for Allan, the campaign has been more than four years long.
Their hard work showed - both were strides ahead of any other candidate.
They are not dissimilar - they are both young, Māori women achieving highly on the political stage.
Allan has been a list MP for one term and she put in the work in the East Coast electorate.
At 28, Tapsell has already been a district councillor for three terms. Her parents tell me she gives everything she tries 100 per cent - my experiences have me inclined to agree.
They have put in the hard yards. For Allan, it paid off. For Tapsell, her time has not yet come.
The East Coast seat has swung. But if Tapsell keeps campaigning and Allan keeps delivering, in three years time we may find ourselves once again saying "the East Coast electorate is the one to watch".