She was parachuted in to the seat among much ill feeling way back:
In 1989, she was elected at the Vauxhall by-election precipitated by the resignation of Stuart Holland. Black candidate Martha Osamor had the most nominations, with Hoey only having one, but the National Executive Committee declined to shortlist Osamor and imposed a shortlist on the constituency party. When the local party refused to choose from the shortlist, Hoey was imposed by the NEC as the Labour candidate.
https://en.wikipedia.org/wiki/Kate_Hoey
And since then, it's far from the first time she's courted the right and deselection. This from 2008, for example:
EXCLUSIVE: Rebel Labour MPs seat could go to gay candidate
A leading Labour party activist has said he is flattered by approaches from party members asking him to stand in Vauxhall.
The current MP, Kate Hoey, caused outrage among Labour members in London when it was announced during the Mayor of London election campaign that she had agreed to become an adviser to Conservative Boris Johnson if he was elected.
She claimed that she was not in breach of party rules banning members from supporting candidates from other parties, and made a comparison with Prime Minister Gordon Browns appointment of a handful of Tory MPs to advisory positions.
However, Labour activists in her Vauxhall constituency are talking openly of deselecting the veteran MP, a former Minister for Sport.
https://www.pinknews.co.uk/2008/05/09/exclusive-rebel-labour-mps-seat-could-go-to-gay-candidate/