The Lib Dems are asserting themselves, as welcome measures in this week’s Budget demonstrate

Danny Alexander’s stature has grown exponentially since he found himself parachuted into the Treasury just weeks after the Coalition was formed

As the saying goes, credit where it’s due. That even applies – perhaps especially so – when the country is up to its eyeballs in debt. It is widely said that George Osborne had a decent Budget this week, aided in no small part by Ed Miliband’s curiously weak response. But the Liberal Democrats, as has frequently been the case during this parliament, made a major and underrated contribution to its success.

Raising the tax-free personal income threshold is the Liberal Democrats’ baby. It is their most popular policy and the achievement that will be heralded in the run-up to the next general election as the party’s key economic accomplishment in government. It has certainly had a serious impact. By the time the increase announced on Wednesday takes effect, the threshold will have risen by more than 50 per cent from its 2010 level. Well over two million people will have been taken out of paying income tax completely.

If the appearance in the Budget of a rise to the basic tax threshold came as little surprise, Mr Osborne’s announcement of significant modifications to the pension system was less widely predicted. While rumours of a shake-up had evidently been circulating; the assumption was that they would be announced next time round. Once more, the Liberal Democrat hand on the tiller is in evidence in this development, with the pensions minister, Steve Webb, steering an impressive course through annuity-filled seas. And again, the decision to grant pensioners more choice over what to do with their savings pot is both popular and substantive. Webb’s off-the-cuff remark about OAPs buying Lamborghinis if they chose to was not facetious – it simply summed up the position.

Danny Alexander’s stature has grown exponentially since he found himself parachuted into the Treasury just weeks after the Coalition was formed. The emergence from the shadows this week of the bright and likeable Webb is also noteworthy in that heightening the visibility of key personnel will be vital to the Liberal Democrats come 2015. There are many in the electorate who would struggle to identify any of the party’s MPs aside from Nick Clegg and Vince Cable. It is encouraging, therefore, to see other capable Liberal Democrats in the vanguard.

Beyond the fact that these Liberal Democrat-inspired policies have gained popular currency, they also show that the party is capable of developing a programme for government within a coherent, liberal economic philosophy. After all, both the raising of the personal allowance and the scrapping of the annuity noose, which had previously ensnared all but the wealthiest, are policies that permit greater freedom and more choice for individuals. Ties to the state and to the annuity industry are curtailed at a stroke. Ten years on from its first publication, the age of the Orange Book may finally have arrived.

If the Liberal Democrats have previously been reining the Tories in, then this week they simply stepped over them. Danny Alexander’s response to Grant Shapps’ “Bingo” tweet – “I thought it was a spoof” – was withering. With a new confidence among the Liberal Democrats, they might be able to look forward to a fuller House after the next election than many expect.