There has been considerable puffing and posturing from the Coalition in recent days over the National Broadband Network, and it continued this morning after the House of Representatives rejected Malcolm Turnbull’s demand for a cost-benefit analysis of the NBN and the Coalition moved in the Senate to block further consideration of NBN-related bills until the business case recently provided to the government was released.

The Coalition’s righteous demands for government documents are completely at odds with its own attitude of contempt toward the Senate on such matters when in government, but political parties are forever discovering the importance of transparency when in opposition — a discovery quickly forgotten when they return to power. It will be thus when the Coalition returns to the Treasury benches.

We’ve been through all this before, of course, with the McKinsey/KPMG NBN implementation study, which the NBN’s critics seem to prefer not to acknowledge whenever they call for a cost-benefit analysis. Senator Conroy was persistently criticised earlier this year for not releasing that study because it was too critical of the NBN, only to be accused, after its release, of manufacturing it because it clearly demonstrated the viability of the network.

The Coalition’s demands for transparency might have some credibility if Turnbull had not been tasked by his leader with the job of “demolishing” the NBN. And in particular, demolishing it without any alternative plan for addressing the ongoing market failure on broadband caused by the telecommunications decisions of the Hawke and Howard governments. The broadband plan the Coalition took to the election is a dead letter, but there has been no replacement policy, despite the insistence of the Coalition — most recently by federal Liberal director Brian Loughnane last week — that another election may not be far away given the fragility of the government’s parliamentary support.

Turnbull has undoubtedly shifted sentiment within the Coalition quite some distance from the bizarrely Telstra-centric views of Nick Minchin, particularly on structural separation. But when he declares “everybody in this House, I am sure, is committed to the availability of fast broadband at affordable prices across Australia” he has a clear credibility problem.

The Coalition’s only stated policy on achieving this is to “demolish the NBN”, and its approach appears to consist entirely of trying at every turn to delay whatever it possibly can.