The bones are thought to have belonged to people from the 11th or 12th centuries, with the body of a small child found amid the remains of 50 adults.
“What the child is doing there is one of the many unanswered questions,” Westminster Abbey’s archeologist Warwick Rodwell told the Guardian.
“It is a feature of many ecclesiastical sites that you find the remains of women and children in places where you might not quite expect them,” Rodwell added.
The child was buried in a wooden coffin, leading experts to believe that he or she was a person of some importance.
The remains were found as workmen demolished a 1950s-era lavatory block in order to make room for a new tower space through which visitors will eventually be able to access the abbey’s attic.
Many of the bones were densely stacked together and experts think they may have belonged to senior clergy given their proximity to the main building, which was itself reserved for kings, queens and nobility.
Westminster Abbey is not the only hub of British power to have revealed dark secrets recently.
In August, the skeletal remains of 30 people thought to have perished during the Great Plague of 1665 were unearthed by construction workers in London’s financial district.
Railway workers discovered the skeletons 350 years after the Bubonic plague engulfed London, as they set about digging up the Bedlam burial ground in Liverpool Street.
A headstone at the historic site marked “1665” was discovered, suggesting that the mass graveyard dates back to the outbreak of the deadly plague across London.
Experts believe the bodies were buried on the same day in individual coffins, which have since rotted away, leaving a mass of distorted skeletons.