The Public Accounts Committee is crucial in the role of Parliament – it does not just scrutinise what the government does in a specific policy area, like a normal select committee. Instead, it evaluates government spending, looking for efficiency and effectiveness of spending of taxpayers’ money. In this instance, the PAC was very critical of the government’s spending on the Great Western Mainline electrification project which has rocketed from £1.6bn to £2.8bn.
The PAC have therefore widely criticised the government on this project and this is a method by which they can attempt to hold the government and their contractors accountable. The fact it made headlines (as in the link above0 is one method by which they hope to encourage the government to be more careful in it’s spending.
A key problem for this, and any, committee is the reactive nature of it however. They often review problems once they have occurred and chastise the government for this. While this is good accountability, it does not prevent the problem from occurring in the first place. In this way, it could be argued that the committee has relatively little power.