The windfall after the Prince turns 30 on June 21 will pave the way for him and his wife Kate to buy their first home, the 'Daily Mail' reported.
"It will be quite a handy sum if he wants to buy his and Kate's first family house. What else would he need the money for?" an unnamed source was quoted as saying.
William and Kate have made apartments at Kensington Palace their London home -- but now they are about to have the money to do some serious house hunting for their first home -- possibly close to Prince Charles' Highgrove retreat.
William can also vary his mother's will to allow brother Harry a greater share of the capital -- in recognition that William will one day inherit the income from the Duchy of Cornwall when his father becomes king.
Diana left a net estate of 12,966,022 pounds after inheritance tax of 8,502,330 pounds was deducted. It is widely believed that with shrewd investment the fund has grown to around 20 million pounds, the newspaper said.
Her estate comprised stocks and shares, jewellery, cash from her 17 million pounds divorce settlement, dresses and other personal belongings at her Kensington Palace apartment.
Diana stipulated that it would be held in trust to be shared equally between her two sons, even though William will inherit income from the Duchy of Cornwall estate when he becomes Prince of Wales.
A spokesman for Clarence House said: "It is a private matter."
