The Queen has refused to employ a man nearly 20 years her junior on the grounds that he is too old.
Ardent monarchist Tom Howl, 67, of Mansfield Road in Wanstead, applied for a job as a visitor guide for the 2011 summer opening of Buckingham Palace.
The sprightly former court usher said: "I am a royalist and collect Royal Family memorabilia so thought that the palace would be a wonderful place to work after I retired.
"I was astonished when I received a letter from them saying they could not employ me because I am too old.
"The Government is encouraging people to work beyond retirement as everyone is now living for longer, but when you actually make an attempt to do so you discover that people cannot employ you."
Although there is now age discrimination law in the workplace, companies can still force employees out at 65 and refuse to employ anyone older.
But with official estimates that as many as one in five people could live to 100, Mr Howl believes Buckingham Palace ought to set a better example.
"I wrote to the Queen during the Pope's visit pointing out that she is still working at 84 and the Pope is still working at 83," he said.
"I received a letter merely restating what the first letter had said. I then wrote to David Cameron expressing my grievances again and received a reply referring me to the Department of Work and Pensions.
"Working part-time gives retired people a chance to stay active, to earn some extra money. They should certainly be allowed to do so."
Buckingham Palace has been asked to comment.