Tanya Miller, a mum of four, took her baby daughter to the raid where she was acting as the getaway driver.
It’s believed the child was in the car seat as Miller drove off just seconds after the robbery took place.
She was jailed alongside her boyfriend, Barry Doswell, 26, and Kevin Docherty, 34.
The robbery took place last April where Docherty entered the Cumberland Building Society in Silloth, Cumbria, and demanded money from a cashier.
The trio were found following a huge police search.
Miller and Doswell pleaded guilty before they were due to stand trial while Docherty entered a guilty plea to robbery and possessing an offensive weapon earlier this year.
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Doswell was sentenced to six years and Docherty to seven years and four months.
Detective Inspector Ian Harwood said after the sentencing at Carlisle Crown Court: “Kevin Docherty subjected the cashiers to a horrendous and needless ordeal whilst making threats brandishing a knife.
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“I’d like to pay tribute to the both the victims and the witnesses to the robbery for their bravery and tenacity in assisting police put these three in prison.
“Understandably this incident caused great distress to innocent members of the public and we are happy that justice has been served and these three people are being removed from society.”
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