Whether you are for or against the Royal Family the one thing you cannot deny is that from a purely financial aspect they are a sound financial entity, not only bringing foreign income into the UK but the Sovereign surrenders the whole of the income from the Royal Estate, Duchy of Lancaster and Duchy of Cornwall in return for the three grants received from the public purse which are all geared to percentages of the income from the Royal Estate. If you look at the figures you will find that it more than pays for itself.
The three grants from the public purse amount to some £1.30 ish per capita per year. If you look at the other side of the coin where the UK had no tourist attractions generated by the Royal Family or the heritage resultant therefrom you would find HMRC requiring more of your income by way of taxes to balance the books.