About £10m of the Queen's private money was invested offshore, leaked documents show.
The Duchy of Lancaster, which provides the Queen with an income, held funds in the Cayman Islands and Bermuda.
A small amount ended up in the company behind BrightHouse, a chain accused of irresponsible lending, and Threshers, which went bust owing £17.5m in UK tax.
The Duchy said the BrightHouse holding now equates to £3,208 and it was not involved in fund investment decisions.