I understand that George III gave up the income from the Crown Estate circa 1760, in return for an income known as the Civil List. That seems to have been a pretty good deal for Parliament. The current Civil List annual payment is £7.9M (unchanged for 10 years) whilst the Crown Estate income is about £200M.
Members of the royal family now seem to have nothing to do with the Crown Estate. The latter is effectively part of government.
What's the Duchy of Cornwall if it is not a Crown Estate?