The outbreak - coupled with a case reported at Windsor Castle - has prompted the Queen to order a crackdown on cleanliness at Royal palaces.
Senior aides have been told to follow strict NHS guidelines - including the isolation of affected individuals to prevent swine flu spreading.
So far employees, rather than members of the Royal Family, have been hit by the highly contagious virus.
But it is understood that one of those affected at Buckingham Palace works in the catering department.
An insider said: "Given the speed this thing can spread it was important that anyone with symptoms, particularly around the kitchens, is kept isolated.
"We don't escape catching swine flu just because of where we work and everyone has been taking precautions. The last thing any if us wants is for it to spread to the Queen or the Duke of Edinburgh."

At Windsor one of the Queen's choristers, who sings at St George's Chapel in the Castle, has contracted the illness.
The Queen usually spends the week at Buckingham Palace and weekends at Windsor. However aides hope her imminent move to Scottish estate Balmoral, where she will spend the summer, will reduce the risk of her catching the bug.
A Palace spokesman said: "As a large and diverse organisation, employing over 1,000 personnel in a number of locations, we accept there are likely to be cases of suspected swine flu. Managers have been briefed to take sensible precautions."
Earlier this week, Prince Andrew scrapped a visit to a factory because of a suspected swine flu outbreak.
He was due to officially open a new factory for digger maker JCB in Uttoxeter, Staffs, and present the £40million plant, JCB Heavy Products, with a Queen's Award for Enterprise.
In other swine flu developments it has emerged that:
The need for more special intensive care beds was highlighted by the case of pregnant Sharon Pentleton, 27, who had to be flown to Sweden for blood treatment after contracting swine flu.
The only UK centre offering such treatment, a five-bed unit in Leicester, was already full - with two of the patients suffering from the virus.
Bruce Taylor of the Intensive Care Society said discussions were being held to put more machines into hospitals. He said: "The provision may not be enough."
Local authorities across the UK have had to make contingency plans in case the death toll dramatically increases.
The council in Exeter, Devon, is preparing for the "remote possibility" that catacombs beneath St Bartholomew's Cemetery could be used to store bodies.
The tombs, carved out in 1832 for victims of a cholera epidemic, are currently a tourist attraction.
Meanwhile Communion wine is being withdrawn from Catholic services and wafers will be placed in people's hands rather than their mouths. The Church of England has already taken the same step.
The Government's new swine flu service sent out 5,584 doses of Tamiflu on its first day last Thursday. By yesterday the number of Antiviral Collection Points had risen from 330 to 1,037.
Health Secretary Andy Burnham said the figures showed "how wonderfully resilient" the NHS was.
This article has 3 comments
One interesting fact about all this is that the first article about the origin of the H1N1 virus was posted more than 2-weeks before first reports of a suspected outbreak in Mexico on March 2nd and basically gives us one of the most important questions we should be asking during this current epidemic. How genetically similar is the 2009 strain of H1N1 compared to that from 1977? If the answer is too similar then we must shift our focus of origins from one of identifying where was the virus fist passed to humans, to a more important who first passed the virus to humans, a point that Cecil's original question asking about the real origin of this disease does not leave out in it's formation.
The time spread pattern of the virus is not only staggering it is unbelievable, a first out of all previous pandemics and deserves much closer study instead of just casting it as the result of higher susceptibility to infection due to increased hygiene practices and higher levels of travel.
By leo. Posted July 27 2009 at 3:23 PM.
It is called swine flu because it originated in swine, passed by direct exposure to humans. By mutation it is able to spread from human to human. So eating pork will not affect the spread of the disease, it is a disease of the respiratory system.
This spread began with a boy in Mexico who had direct contact with swine with "swine Flu", hence why the origin of this disease is located in Mexico.
Our hygiene habits are highly sophisticated now which means that we have only the most sophisticated virus's to combat and some experts believe that because our hygiene levels are so high we do not always have the tried and tested immune system that our less advanced counterparts had in the past.
Yes we do travel more these days and this is why these diseases spread so fast, the highly contagious ones anyway. How many thousands of people fly from one country to another every day???
You should Google more before you post Cecil.
By Kate. Posted July 26 2009 at 11:08 AM.
It is still puzzling to know the real origin of this disease. To say that it began in Mexico is not enough. For it to have spread to 160 countries is staggering. Are we to understand that too many people are traveling too widely or our habits of hygiene are so ghastly lacking? Can H1N1 be a mutation of H5N1(Avian Flu)? And to hear that eating pork is permissible diminishes the aetiological roots. It only leaves us with the question: "Why is it called SWINE FLU?"
By Cecil Archer. Posted July 26 2009 at 4:05 AM.