A likely 0.25 per cent rise would put at extra £11 a month on the average mortgage of £87,000.
After the Governor's speech the City of London is speculating that the increase will come before the end of the year, rather than next spring.
More than 7 million homeowners have variable rate mortgages, which track the Bank's base rate or the lender's Standard Variable Rate or SVR.
That's 65 per cent of all mortgage borrowers. The rest, on fixed rates, wouldn't be affected until their mortgage deals expire.
Some of those paying SVR might also be protected for a time, if their lenders decide not to pass on an increase.
Mortgage experts are also warning that new fixed rate deals could soon become more expensive as the financial markets begin to anticipate an earlier rise in rates.