Profits from Britain's royal residences fell by 24 per cent last year.
The latest accounts show the attractions earned £6.9 million from April 2013 to March 2014, but these profits fell to £5.2 million the following year - a decrease of £1.7 million.
The accounts filed by Royal Collection Enterprises also show the total number of visitors at the attractions fell by more than 80,000 from the previous year's total of 2.55 million, with an 11 per cent decrease in visitors at London's Buckingham Palace alone.
The Daily Mail newspaper reports sales of merchandise have also plummeted by 19 per cent, with the huge drops being blamed on the "Kate effect", suggesting the public are losing interest in the royal family following the royal wedding of Duchess Catherine and Prince William in 2011.
In the year subsequent to their wedding at Westminster Abbey, profits surged with £10 million in ticket sales being recorded as well as a record number of visitors at Buckingham Palace as members of the public rushed to see the Duchess' wedding dress which stood on display.
A spokesman for the Royal Collection Trust explained: "The decrease is largely due to the absence of a special royal event."
Since the Duke and Duchess of Cambridge got married, other milestone events have included the Queen's Diamond Jubilee and the 60th anniversary of the Coronation.