Localism Bill

I did not give notice of my intention to ask a question about Clause 4, but I have listened to the discussion on the previous group of amendments with some interest. Clause 4(1) gives me a certain amount of anxiety. The provision describes, "““power on a local authority to do things for a commercial purpose only if they are things which the authority may, in exercise of the general power, do otherwise than for a commercial purpose””." Does that really just mean that if it is illegal to do it otherwise, they may not do it for a commercial purpose, or is there some inwardness here which perhaps I have not appreciated? It sounds almost tautologous. If a local authority cannot do something, presumably it cannot do it whether for a commercial purpose or otherwise, in which case why put it in the Bill? If there are differences or some distinction is being drawn here, I would be most grateful if my noble friend could explain it to me.