What is the Bank of England base rate?

This is the interest rate the Bank of England charges on money lent to financial institutions, including HSBC. The Bank of England's Monetary Policy Committee generally meets once a month to decide whether this rate should change.

Why does it matter to me?

Any change in the base rate can influence the rates of existing or new products which are available through financial institutions, including HSBC. This is because the cost of providing some products is directly linked to the base rate.