14/08/2014 16:45 BST | Updated 20/05/2015 10:12 BST

Prince William And Kate Middleton's Kensington Palace Refurbishment Cost £3.8 Million

It's not just their Anmer Hall country house on the Queen's Sandringham Estate that Kate Middleton and Prince William have spent big money on refurbishing. The couple's Kensington Palace apartment was redesigned at a sum rumoured to be just under £1 million last year.

But that modest million is said to have seriously increased. E Online reports the renovation costs for the royal couple's Kensington Palace digs have almost quadrupled and the grand total is now estimated to be around £3.8 million.

A spokesperson for the royal couple said: "This is the Duke and Duchess' one and only official residence. It is here that they plan to stay for many, many years to come. They were also at pains to ensure that the specification is not extravagant," reports E Online.

Really,"not extravagant"? While we're all for Kate, Wills and Prince George making their four-story, 20-room apartment homey, £3.8 million is pretty hefty.

Given that the duchess has been seen shopping at Zara home and the couple are said to have paid for fixtures and fittings themselves, what's caused this refurb figure to rise so significantly?

Maybe they forked out on a swanky new kitchen with all the bells and whistles? Or was it Prince George's two nurseries that cost a bomb?

Either way, it's public funds and HM the Queen covering costs. (That's after she spent £8 million on a helicopter for William's 32nd birthday in June.)

LOVE THIS ROYAL COUPLE? Click through this gallery of photos to see more immaculate style from Kate Middleton and Prince William.