As Queen Elizabeth II becomes the UK’s longest serving monarch, Rentify has evaluated how much each of her residences may have cost if she were renting.

The figures from Rentify put Buckingham Palace as the most expensive of the Queen’s residences, estimating a rent of £303,340 a month for the 240-bedroom central London property. This saw the Palace eclipse the average rent for the SW1 area by almost 2,000%.

Overall, Her Majesty’s seven properties would have racked up a combined rental bill of more than one billion pounds (£1,037,277,892) throughout her 23,227 day reign.

By comparison, the Duke and Duchess of Cambridge’s residence of Anmer Hall is estimated to command £14,000 a month.

Second on the royal rental rich list was Windsor Castle, with the Berkshire property estimated to command a rent of £129,375 PCM for its 225 bedrooms and 13 acres of land – 5,265% higher than the average rent of a four-bedroom home in the area (£2,300 a month).

“Royal properties will always command a royal price tag, and these estimates show that even royalty would not be exempt from the effect of astronomic London rents,” said George Spencer, CEO of Rentify.