Can big, long speeches about economics made in the House of Commons on a weekday lunchtime ever pack enough punch to shift the mood of the entire nation?

Of course not. Budgets take time to filter through to the public – days and possibly even weeks. And even then, their impact is limited to those who are willing to notice.

I’ve looked at the opinion polls a month before and a month after each of the Budget speeches delivered by George Osborne. There’s really only one instance when there was a marked change: 2012, the year of the “omnishambles”:

Here, the gap between the Tories and Labour went from 1.6 points to 7.6 points. But compare this with what happened in the polls just 12 months earlier:

Virtually no change.

Last year’s Budget came halfway during a narrowing of the gap between the two main parties:

This trend was more to do with a decline by Labour than an increase in support for the Tories, however.

A similar pattern applies to 2013:

That just leaves 2010: the only occasion in this parliament that a Budget has taken place when the Conservatives were ahead in the polls.

This Budget was the first real political event after the general election, and I wonder if it crystallised in a lot of people’s minds their attitude towards the coalition, in particular the role of the Liberal Democrats. A marked shift in support away from the Lib Dems began around the time of this Budget and continued for several months, the legacy of which the party is still living with today.

A month before this year’s Budget, Labour had a lead over the Tories averaging 1.5 points. Its current lead is averaging 0.8 points. One month from now we’ll know whether this particular trend has behaved like those of the last couple of years. George Osborne for one will certainly be hoping it does.