The reasoning behind this would be to ensure that there were negative real interest rates.
If the Bank of England commits itself to producing significant inflation then real interest rates could become negative.
Thus people might borrow money (at 0% interest) and repay in their (devalued) pounds.
This would give people a significant incentive to borrow and spend.
A little more inflation might be preferable to rising unemployment or a series of fiscal measures that pile on debt bequeathed to future generations.The idea of negative interest rates may strike some people as absurd, the concoction of some impractical theorist. Perhaps it is. But remember this: Early mathematicians thought that the idea of negative numbers was absurd. Today, these numbers are commonplace. Even children can be taught that some problems (such as 2x + 6 = 0) have no solution unless you are ready to invoke negative numbers.