Better a lucky central banker than a correct one?

Better a lucky governor than one who's always right. At least, that's what Mark Carney will be hoping for as he faces politicians on Tuesday – almost a year to the day since he took over as Bank of England Governor.

After all, the Treasury Select Committee could find plenty of things to quiz Carney about. A starter for 10 would be his scattergun communication record on interest rates. His volte face on rates this month caused short-term borrowing costs to spike in the biggest one-day jump since 2009, back when the U.K. was in the midst of a financial crisis.

The Monetary Policy Committee minutes may say the Bank was surprised a rate rise hadn't been factored in earlier – but most participants would argue they had simply trusted the governor.

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But it's not just Carney's credibility in the bond market that's at question. The governor got it wrong on his unemployment target, on the pace of recovery in the U.K., and his fuzzy guidance has been, well, fuzzy, testing the patience of politicians and borrowers alike.

Peter Macdiarmid | Getty Images

Certainly, even Carney can't pretend to have got it right in his forecasts about the pace of Britain's recovery. Until recently, the "guidance" seemed to be that Carney was in no big hurry to raise rates – believing the economy was still fragile.

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However, on Friday, official figures are expected to show growth continued to steam ahead in the first three months of 2014, increasing to 0.9 percent from the last reading of 0.8 percent. When combined with the latest numbers showing unemployment is down to 6.6 percent, it hardly seems justifiable to continue with emergency level-interest rates.

Instead, action was expected to be targeted at house prices, which have soared 9.9 percent over the past year, or 18.7 percent in London alone. Herald the return to 1970s-type credit controls in the mortgage market, rather than hiking interest rates across the board.

Read More'Unsustainable' boom in UK property to cool by 2016

Except, now Carney seems to be saying something completely different, with suggestions we will have both a new set of macro-prudential tools and a rise in rates – bad news for first-time borrowers.

So maybe politicians can question the Governor about why he chose to upstage this Thursday's crackdown on the mortgage market by the Financial Policy Committee. Perhaps it is lucky again then that the Bank's self-imposed purdah will prevent Carney answering clearly.