Does your mortgage state that it will track the Bank of England base rate as long as it doesnt go below a floor of 2.75%?
If so, Nationwide have decided to waive this floor and it will just follow the base rate.
Eg..your mortgage rate is 1.13% over the Bank of England Base (2%) rate which will not go below a floor of 2.75%. This will mean your rate will be 3.13% as opposed to 3.88% and then this will further track the Bank of England base rate...
Link in first post.