The blueprints for security upgrades to the Kensington Palace apartment Prince William and Kate Middleton will soon call home have been made public, exposing the high-profile royal couple to potential security threats, royal and security experts say.

The planned, updated protection measures for the Duke and Duchess of Cambridge's new home, which they plan to occupy next year, were made available for public viewing yesterday at the request of the local Kensington town council.

Members of the public can see the upgrades, said to include an "air lock" double-door system, advanced CCTV system, special pop-up bollards and spiked railings, at the Kensington town by showing just a passport or driver's license photo identification.

The potential security breach comes the same week that a dead body was discovered on the grounds of the royal family's vacation retreat at Sandringham Estate, just one mile from the home where Queen Elizabeth and Prince Philip are currently staying, and where Prince William and Kate joined them to celebrate Christmas.

"After the queen, they are the most important members of the royal family," Dickie Arbiter, former press secretary to the queen, told ABC News, of Will and Kate.

"Therefore, they are very much the most at risk," he said.

The Kensington council says it is following guidance issued by the central U.K. government and not backing down, despite a plea from Buckingham Palace to keep all security measures for the couple's home private.

"We would appreciate if this application could be treated as confidential and not be allowed to enter the public domain, owing to the nature of the works and their location," Roy Brown, an official with the Palace's property department, wrote in a letter to the Kensington and Chelsea council.

A council spokesman responded publicly, saying, "We don't allow people to take photographs of the drawings or take copies away, but they are allowed to see them if they show a passport or driving license and are asked to look at them with a planning officer."

The plans are not available online.

"Perhaps it's going to take some sort of legal action to prevent anybody from looking at these things," Arbiter said.  "Why they [the council] are not bending to the request from Buckingham Palace…I really don't know."

The planned upgrades are estimated to cost around $750,000, while around-the-clock security staff for William and Kate could cost up to $3.8 million per year, according to the UK's Mirror newspaper.

The couple, married last April, plan to move into the 300-year old property next year, and use it as their London home for weekend and official visits.  Their primary residence will remain a small house in Anglesey, an island off the coast of northwest Wales where William serves as a Royal Air Force helicopter rescue pilot.

William and Kate currently have a temporary home on the palace grounds while their apartment, formerly the home of the late Princess Margaret, the queen's younger sister, is remodeled.

William grew up in Kensington Palace, living there as a child while his parents, Prince Charles and the late Princess Diana, were married, and then staying on with his mother after their divorce.

Princess Diana used the palace as her primary residence until her death in 1997.

William and Kate will share space with other royals who also live in the palace, which is broken up into a number of apartments.