A former business manager at the school, Millar was made redundant less than three weeks before she was due to turn 55 and would have been eligible to withdraw from her pension.
Under UK legislation, people can start withdrawing from their pension once they turn 55, with 25% of this available as a tax-free lump sum.
Millar appealed to delay the process, however The Oak Trust, which runs the primary school, denied her appeal.
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It said: "The trust would be failing in their responsibility as guardians of the public purse if they manipulated a timeline for your financial self-gain."
Audrey Williams, employment partner at law firm Keystone Law, said despite good intentions, employers can run into legal implications if their actions amount to discrimination.
Speaking to HR magazine, she said: “Those responsible for managing public finances are required to consider carefully how they use such resources. By prioritising saving money, the school treated her less favourably because of her age.
“Previous cases have made clear that even where an employer has what might be considered a 'good' motive, if detrimental treatment occurs because of age (or other forms of discrimination), an employer is unlikely to be able to defend its decision or approach.”
Millar, who was dismissed despite her pleas, took The Oak Trust to an employment tribunal and is now expecting a payout.
A hearing will be held to determine the level of compensation.
The judge ruled Millar's upcoming 55th birthday was a 'significant motivator' to the trust's approach.
Williams said employers should never use artificial deadlines during redundancy processes.
She said: “At the heart of this decision is the Tribunal’s conclusion that the redundancy consultation process was accelerated to ensure the claimant’s employment was terminated before her 55th birthday.
“A younger employee would not have faced an accelerated process, and that amounted to direct age discrimination.”
