A Reuters poll of economists had shown a median forecast of a fall to 3.5 per cent in November's annual inflation rate, though the BoE had pencilled in a slightly bigger drop to 3.4 per cent.
Sterling dropped by about half a cent against the US dollar after the official data came out on Wednesday, which reinforced expectations for looser monetary policy.
Financial markets have been pricing in a more than 90 per cent chance of the BoE cutting rates by a quarter point to 3.75 per cent on Thursday, though many economists have said they see the decision as more finely balanced.
Wednesday's data showed services price inflation, which the BoE sees as reflecting as a guide to longer-term inflation pressures, fell to 4.4 per cent rather than holding at 4.5 per cent as economists and the BoE had expected.
Food and non-alcoholic beverage inflation dropped to 4.2 per cent from 4.9 per cent in October.
The BoE has said it expects this to rise 5.3 per cent in December, the highest in nearly two years.
Core CPI - which excludes more volatile food, alcohol, energy and tobacco prices - also slowed to 3.2 per cent rather than holding at 3.4 per cent as economists had forecast in the Reuters poll.
The BoE's Monetary Policy Committee in November voted 5-4 to keep interest rates on hold, breaking the quarterly cadence of rate cuts in place since 2024 and economists expect a December rate cut by only a narrow 5-4 margin.
Of those members who opposed a cut in November, governor Andrew Bailey looks most likely to switch votes as he said in minutes of the decision that he wanted to see further falls in price pressures "this year" before backing a cut.
British inflation has been higher than in other major advanced economies and in November the central bank forecast it would remain above its two per cent target until the second quarter of 2027.
Since then, finance minister Rachel Reeves announced measures in her November 26 budget that will shift climate change costs away from levies on energy bills towards general taxation.
