Queen Elizabeth II fears a referendum on independence in Scotland can lead to a break-up of the United Kingdom.
The monarch is so worried that she has held a crisis meeting with Prime Minister David Cameron following Scottish National Party (SNP) moves to hold a referendum on the issue.
A Buckingham Palace source said both Cameron and the Queen were taking the SNP’s threat seriously enough to plot against it.
The Queen raised her concerns with Cameron after the SNP’s surprise victory in the Scottish Parliament Elections earlier this month.