The British royals, who trace their history back more than 1,000 years, could be gone within two generations, writer Hilary Mantel said in an interview published on Saturday.

The monarchy traces its history back at least to William the Conqueror, who invaded England in 1066, but also claims ties to the patchwork of kingdoms and principalities which stretched across what became England, Scotland and Wales long before that date.

Mantel, best known for her Wolf Hall trilogy that traced the rise of...