As the Hansard record shows, in January 2010, he was tearing into the then Labour chancellor Alistair Darling's proposed "Financial Responsibility" bill, which sought to enshrine in law a Labour pledge to halve the deficit in two years. Fast forward nearly five years, and chancellor Osborne himself is now keen on pushing his own very similar bill (or "charter"), despite having once labelled such measures a "con".
This isn't the first time the chancellor has performed such a shameless u-turn on getting into government. Here are four more moments that show the two faces of George Osborne: before and in government.
As shadow chancellor, Osborne railed at bankers' "unacceptable" bonuses and called for to get just £2,000 in cash.
As chancellor, Osborne leapt to defend bankers' bonuses from the threat of a bonus cap being imposed by Brussels, a struggle that he later abandoned after spending at least £20,000 of public money on lawyers.
In 2007, Osborne not only pledged to match Labour's spending plans but to spend more than them. The pledge was later ditched and now the Chancellor loudly attacks the party for being "totally irresponsible" with the public finances by following the same programme he pledged to match.
In 2009, shadow chancellor Osborne insisted that "under a Conservative government the Treasury will no longer be the cuckoo in the Whitehall nest when it comes to climate change."
But in 2011, the chancellor was clearly fed up of trying to cut carbon emissions, telling Tory activists: "We're not going to save the planet by putting our country out of business.
"So let's at the very least resolve that we're going to cut our carbon emissions no slower but also no faster than our fellow countries in Europe."
In April 2010, shadow chancellor Osborne made very clear that he didn't need to raise VAT to cut the deficit, explaining: “The tax increases are already in place, the plans do not include an increase in VAT."
He stuck to this line, even when the Lib Dems used a campaign poster to accuse the Tories of planning a "VAT bombshell".
Just two months later, new chancellor Osborne decided in his emergency Budget to do just that - increasing VAT to 20% - as he insisted it was "unavoidable".