Does The Royal Family Use Tax Avoidance Vehicles?

This is probably a most unworthy thought for such a loyal subject as myself to have, but given that the Queen now actually pays tax one can't help but wonder whether she or any of her immediate family are the beneficiaries of any schemes the purpose of which is to legitimately minimise their tax liabilities.

I realise that in some circles that question might be regarded as being as tasteless as asking whether any of them have offshore bank accounts - Heaven forbid - but if their advisers have allowed such schemes to be set up on their behalf then that would send out a very poor message to the rest of us. Even if the person in whose name tax is collected isn't aware that they aren't paying as much as they could, what message about paying tax does that send to the rest of us?