In a speech last June, the MPC's Adam Posen stated that it was "difficult to attribute the rise in inflation in the UK solely or even primarily to "one-off" factors like VAT, past sterling depreciation, or energy prices". Instead, "the most logical and empirically reasonable explanation for inflation creep is some unanchoring of inflation expectations, caused by the series of above target outcomes for UK inflation in recent years".

Such views suggested some common ground with his hawkish MPC colleague Andrew Sentance but Dr Posen has long since moved on. In a speech last week he claimed that, but for sterling depreciation, core inflation excluding indirect taxes and energy "would have been below its long-run trend (that assumed consistent with meeting target headline CPI inflation in the future)". Meanwhile, "long-term inflation expectations ... remain anchored".

Dr Posen changed his policy position in September last year, soon after the US Federal Reserve signalled its intention of launching QE2 asset purchases. In a speech at the end of that month, he called for similar action in the UK, not on the basis of any new data but because "policymakers should not settle for weak growth out of misplaced fear of inflation". He registered his first vote in favour of such a policy at the October MPC meeting.

Dr Posen is a close academic colleague of Fed Chairman Bernanke and shares his view that the post-crisis environment is fundamentally deflationary, echoing Japan in the 1990s and the US and Europe in the 1930s. With this prior, it is hard to conceive of data developments that would persuade him to vote for policy tightening any time soon. Dr Posen, however, may face a dilemma later this spring if, as seems likely, the Fed shifts to neutral and signals no further extension of QE.