On 6 July 2005, Team GB won the 2012 Olympic Games. Some 70% of UK people backed the bid and Prime Minister Tony Blair was feted for his part in the successful pitch. It was, in his words, “A huge moment of triumph and celebration.”

Winning the world’s biggest event – David Cameron is expecting a £13bn return on our £9bn outlay – delivered global prestige for little political risk. London was an outside chance to win the Games. So while failure would have been criticised, the headlines would have blown over quickly. The benefits of winning, on the other hand, were huge.

Delivering is another matter.

Yes, there is still a significant political upside: an international stage to preside over, a sense of national pride to leverage – and what should be a welcome and positive distraction from economic woes. But the downside is far more significant. While 30-mile tailbacks and “shambolic” security contracts have their roots some distance from the Cabinet table, they have fuelled a wider narrative about government incompetence that is starting to take hold.

Competence had been a strong suit for the Coalition until recently. Unpopular cuts had been counterbalanced by the perceived managerial qualities of the government. But that central pillar of the Coalition is starting to crumble. Treasury gaffes and U-turns are widely seen as the starting point, and media pressure is feeding through to polling numbers. A Populus poll in the Times – in the week that the IMF cut its UK growth forecast to 0.2% from 0.8% a – showed only 34% think the Conservatives are “competent and capable”: a drop from 46% in March.

When the next fiasco comes along, a reputation for incompetence is a magnet for blame. But aside from personally driving every bus to the Olympic Park, there is little that Cameron can do to control popular perceptions of his government over the next few weeks. Best cross his fingers, hope we win some medals, and maybe look for chinks in Boris Johnson’s Teflon armour.

Jon Bennett is a director at public relations and public affairs consultancy Linstock Communications