UK mortgage lenders vary their interest rates in line with the Bank of England's base rate. This can mean repayments go up, or down, depending on the change. According to the Council of Mortgage Lenders more and more people are opting for variable rate mortgages.
A standard variable rate mortgage allows the lender to set interest rates. Changes made to the base rate will have an effect, but there may be a delay before your mortgage provider consequently alters their rate.
Other types of variable rate mortgage include the tracker, which adjusts without delay. If you want to be sure your payments track the Bank of England's base rate, you should opt for this kind of mortgage.