Statistics and Registration Service Bill

I know that in the past 10 years, under the current Chancellor of the Exchequer, the Treasury has taken considerable interest in a wide range of issues affecting many Departments. However, things might change when the Chancellor of the Exchequer changes. Therefore, I am still not clear why the Treasury is a better Department to perform the role in question than the Cabinet Office, which will have that kind of overview role and which is less likely to change in that way.