Here's an idea then temporary, make it into a hospital, you know those things that are necessary in life. The cost of running it could be afforded if there were no Royal family, and those 300 employees you mentioned could be retrained and put to better use than running round after one family.
Very simplistic and far fetched? maybe but I'd rather that than what we have now. National health at breaking point, police stretched to the limits, public services cut to the bone, food banks, bedroom tax, sanctions......the country's at breaking point. But never mind we've got a royal family, we'll all be fine. 