The security arrangements around Prince Harry and Meghan could cost £ 5m, said sources.
The Duke Sussex and the Duchess are transforming Frogmore II's listed Frogmore II next year.
The latest plans for property, on the grounds of the Windsor castle, are kept secret, but they include official protection attachments.
Royal Protection Officer Officer Ken Wharfe said: "Construction and safety arrangements can cost £ 5million in the first year of the balloon.
"Frogmore is not helpless, no one lives. There are at least two or three official cost protection officers and he has to take care of the police at the Thames Valley Police.
"They should have major reviews about property security almost from all sides."
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He added: "The rise of the taxpayer will be dramatic. Thames Valley does not differ from any other 20-25% cuts that have been seen by the cuts, the budget will be strained.
"Mammoth is a task. Fitting and maintenance of safety equipment costs, with more officers in the area, would cost more than one million dollars a year."
The five-bed house has a public thoroughfare of 200 meters long. The entrance to the castle is farther, but beyond the open examination.
In many places, the only six-foot wall is separated by public roads. Mirror understands the strength of local Thames Valley, Met Police and selective supporters have extended talks on security plans.
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An operation-related source said plans have discussed a cabinet room from home, a gift from Queen.
This will be the subordinated subsidiary of the passive subject. Worker Kensington MP Emma Dent Coad said: "In a homeless homeless, how can that be justified?"
Harry, Zambian yesterday, met the Queen's Commonwealth Trust Circus Zambia and plans to cover decorative costs for Meghan.
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Board officials have approved a planning application to restore ownership and install two-page extensions.
King Newlyweds, his first child in spring, lives in the Kensington Palace in London, where he hopes to go to another apartment.
Met Police said: "We do not mention issues related to security protection." The Kensington Palace does not mean.