Government fails because it does not have sufficient incentive to improve. Such an incentive can only come from external accountability. Ultimately, external accountability must derive from Parliament. Debate on the floor of the House of Commons provides a very crude form of accountability. Although it rarely if ever now results in a ministerial resignation, sometimes the Prime Minister is embarrassed into sacking the minister.

Sanctions should be based on accurate assessment of performance. The only mechanism Parliament has for this is its select committees. The Public Accounts Committee (PAC) is the oldest and perhaps the most important of these and works by considering about 50 reports per annum from the National Audit Office (NAO). The Comptroller and Auditor General (the head of the NAO) is an officer of the House of Commons, and so in theory should be independent of government. In fact, NAO reports have the reputation of being somewhat overcautious in their conclusions. A report produced in June 2006 on the National Programme for IT in the NHS was widely regarded as a whitewash. PAC did not report on the programme that year, but in 2007 produced a much more critical report, clearly based on other evidence. Another limitation of PAC is that the large number of reports it considers means that it typically only hears one day's evidence on each report.

Select committees in general are often hampered by lack of access to crucial information. In theory both Houses of Parliament have the right to call for 'persons, papers and records', and the House of Commons has extended this power to its select committees. In practice committees have no means of enforcing this right and so have to work within rules set by the government. Underpinning these rules is the principle that civil servants only speak to committees on behalf of their minister. In other words they can explain the reasons ministers choose to give for a given course of action, but not the options considered or the advice given internally. The sole exception to this rule is that heads of departments, in their role as Accounting Officers are responsible to PAC for running their departments with 'regularity, economy, efficiency and effectiveness'. So weak is the position of the committee however, that civil servants rarely embarrass their political masters.

An especially notorious example of the lack of government co-operation with committees was over the Foreign Affairs committee's attempt to examine the events leading up to the Iraq War. This was in stark contrast to the co-operation given to the Hutton and Butler enquiries set up by the government.

In spite of these limitations, select committees often produce excellent and critical reports. However neither House ever votes on the recommendations of these reports, and so there few consequences for the government.

Whilst government dominance of the House of Commons is the obvious explanation for its deficiencies, the journalist Peter Oborne suggests that opposition MPs pull their punches because they have more in common with government MPs than with those who elected them.