Prince Harry is reportedly set to inherit £8 million from the late Queen Mother when he turns 40

At the time, the Queen Mother, who was then 94, apparently put aside a tax-free £19 million to leave to her great-grandchildren, according to The Times.

The newspaper added the inheritances were divided into two installments - one to be given to Princes William and Harry when they turned 21, and another on their 40yth birthdays.

A former palace aide told The Times: "There was a trust fund set up at the time.

It was a way in which the Queen Mother could set aside money for when her great-grandchildren were older and a way of passing a slice of her estate down in a tax-efficient way.

"It was a way in which some of her estate could be ring-fenced for them."

Sources added Harry may have been left more money than his older brother William, 42, in the inheritance.

Insiders say it is due to the face the Queen Mother assumed William would get a larger fortune from the Duchy of Cornwall as Britain's future heir.

William became Duke of Cornwall when he was made Prince of Wales after King Charles' coronation, and is estimated to have got a £23.6 million fortune by inheriting the estate.

When the Queen Mother died in 2002 aged 101, a statement from Buckingham Palace said: "Queen Elizabeth The Queen Mother has bequeathed her entire estate (which mainly comprises the contents of her houses) to The Queen.

"In her will, she asked The Queen to make certain bequests to members of her staff, and these bequests will be subject to inheritance tax in the normal way.

"The Queen has decided that the most important of Queen Elizabeth's pictures and works of art should be transferred to the Royal Collection."