The Government faces one further crucial parliamentary test before the summer holidays: on an issue that has attracted far less public attention than either 42 days' detention or the Lisbon treaty but which is much more likely to come into operation and have a wideranging impact.

The Planning Bill proposes to streamline and accelerate decisions on big infrastructure projects such as nuclear power stations, waste sites, airports, wind farms and motorways.

The final Commons stages have been delayed by more than a fortnight already in an attempt to defuse opposition by backbench Labour MPs, and they will now take place next Wednesday.

The stakes are high. The Government believes that the Bill is vital if big projects of national importance are to be built as soon as possible to secure Britain's economic, and especially energy, needs. The critics argue that the proposals undermine accountability to local voters and to Parliament.

The central argument is over the proposed infrastructure planning commission, which would decide development consents for important projects, possibly 45 annually, within an overall government policy.

This is in line with Gordon Brown's other attempts to “de-politicise” sensitive issues via the Monetary Policy Committee and the Competition Commission. The aim is to bring down the average time for decisions to within a year, rather than the several years under current planning inquiries.

Critics argue that this new quango would tear up a long-established framework and would be both unaccountable and undemocratic, reducing the scope for local protests, while leading to legal challenges probably. Even normally loyal Labour MPs argue that the final say on big planning issues should be taken by elected politicians.

An amendment requiring final decisions to be taken by the Secretary of State, with the commission acting in an advisory capacity, has been backed by more than 60 Labour MPs, as well as opposition parties.

John Healey, the Local Government Minister, has been very busy talking to concerned MPs. He wants to sort these issues out before the Bill goes to the Lords, where it could face substantial problems.

The word from Whitehall is that the emphasis in the talks has been on persuasion and reassurance about the role of MPs in approving the national guidelines, rather than on making substantial concessions. Mr Brown is firmly behind the Bill, as are the main business organisations.

John Hutton, the Business Secretary, who supports strongly a new generation of nuclear power stations, has said: “It is essential to win. The Government should stick to its position and we will.” He believes that any weakening of the Bill risks delaying important new power stations and other infrastructure projects.

This has become a classic battle over global competitiveness versus political accountability and local rights: in short, about one of Mr Brown's key long-term priorities.

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