Tax policy, forecasting, and Treasury reform attempts

What does Treasury control of tax policy mean in this discussion?

It concerns which taxes are levied and where, alongside Treasury advice, while the wider answer also considers forecasting and attempts to transfer economic functions elsewhere.

Tax policy means deciding which taxes are levied and where they apply, with the Treasury advising on those choices. Economic forecasting is another function discussed alongside that authority. The Office for Budget Responsibility's creation in 2010 is cited as a transfer of forecasting work out of the Treasury. An earlier Department for Economic Affairs is recalled as an attempt during 1964-1967 to take over some responsibilities before they returned to the Treasury. The Bank of England supplies another example of an institution gaining independence while Treasury influence continued.