What matters is whether these assets were sold below their market values or not. I suggest they were not. His other line of attack was that privatisation has failed because, according to him, future economic benefits exceeded sales revenue. Privatisation is a financial failure. The economic case for privatisation rests on the superiority of markets in allocating factors to their most valued and hence efficient uses.
Sales revenue has nothing to do with it.
The logic of the market case is that efficiencies arising from privatisation will raise general economic welfare. Hazelwood power station is my favourite example. But according to the likes of Odgers Hazelwood must have only had scrap value. Privatisation of power plants has resulted in productivity rising by about 250 per cent while prices also fell. Now it is true that prices falls have been the result of excess capacity.