Moira Cameron, who was the first Yeoman Warder at the Tower, claimed to be a victim of bullying in a campaign which included colleagues tampering with her uniform and leaving notes in her locker.
A third member of Ms Cameron’s male colleagues is currently under investigation, the Guardian reports.
It is also alleged that her Wikipedia page was defaced by one male Beefeater and it is believed he has received a police caution under the Communications Act 2003 following an investigation.
Ms Cameron, from Argyll, in Scotland, became the first female Beefeater in the summer of 2007, after serving in the armed forces for 22 years.
In a statement, the Tower of London said: "We take such allegations very seriously and our formal harassment policy makes it clear that this is totally unacceptable."
Beefeaters are ceremonial guards of the Tower and are responsible for safeguarding the Crown Jewels, along with any prisoners.
They also work as tour guides.
