Bank of England policymaker Kristin Forbes said on Thursday she feared the pound's weakness would have a lasting upward effect on inflation, and that she was concerned central banks were becoming more reluctant to raise rates than in the past.
Forbes - whose three-year term on the BoE's Monetary Policy Committee ends next week - has voted since March to raise British interest rates from their record-low 0.25 percent.
In her final speech as an MPC member, she expanded on research she published last week which argued that sterling weakness had a longer-term effect on inflation than the BoE typically assumed.
"'Lift-off' of UK interest rates should not be delayed any longer," she said in a speech at the London Business School.
"Sterling's depreciation has fundamentally shifted underlying inflation dynamics in a way that makes it more pressing to begin this voyage soon."
Forbes's remarks come after a turbulent seven days which have seen a big split emerge on the MPC at a time when inflation is picking up but growth prospects are unclear as the country prepares to leave the European Union.
Two other policymakers unexpectedly joined Forbes last week in voting for higher rates, and the BoE's chief economist has said he is likely to do so later this year once the "dust cloud" around Britain's political outlook has cleared.
One major bank, Nomura, said earlier on Thursday that it expected the BoE to raise rates at its next meeting in August - far earlier than the 2019 date given by most economists in a Reuters poll at the start of the month.
But BoE Governor Mark Carney has poured cold water on the chances of a rate hike, highlighting "anaemic" wage growth which is likely to drag down on inflation once the effect of currency weakness fades.
Britain's economy slowed in the first quarter of this year after an unexpectedly robust performance in 2016, though the BoE expects reasonable growth overall this year and next.
"The UK economy appears to be solid enough on key economic criteria, and even 'overstimulated' by others, such that a moderate reduction in the substantial amount of monetary stimulus ... makes sense," Forbes said.
Weak wage growth - a factor cited by both Carney and policymaker Andrew Haldane - was not a good enough reason to hold off from raising rates, given Britain's low productivity and other price pressures.
"A key lesson from monetary history is that a tightening cycle should start before wages accelerate to reach their level consistent with sustainable 2 percent inflation," Forbes added.
Forbes said that a potential weakening in consumer spending, and the effect of a rate rise on sterling, were concerns for those of her colleagues who did not want to raise rates yet.
But she said the fact that the U.S. Federal Reserve is raising rates should reduce the impact on sterling of a BoE rate rise, as should markets' current focus on Brexit talks rather than the monetary policy outlook.
The United States' experience also suggested that household saving rates could fall further to support consumer spending if needed, she added.
Reluctance
Forbes said both the BoE and the U.S. Federal Reserve appeared less willing to raise interest rates than in the past.
Possible reasons for this included greater accountability and public scrutiny than in earlier decades, which could make policymakers unwilling to take measures that were unpopular in the short-run.
Another factor for the BoE could be its new responsibilities for financial stability, which gave senior BoE staff on the MPC less time to look in-depth at emerging inflation threats and challenge any internal consensus.
Tighter BoE mortgage rules in 2014 were one factor that Forbes said had made her pause for thought over raising rates.
"These institutional changes may provide substantial benefits for the central bank as a whole and overall economy, but these changes may also have played a role in making it more difficult to increase interest rates," Forbes said.