Hamilton Island's billionaire Oatley family has been ordered by Queensland's Supreme Court to allow the sale of a house built by the late Beatle, George Harrison, to a Melbourne property developer for $8.5 million.

The international trustees for Mr Harrison's estate sued Bob Oatley's Hamilton Island Enterprises because it would not allow the assignment of the sublease on the house to Northaust Leisure Pty Ltd, a little-known Melbourne developer that is headed by George Adams.