What's causing the UK's long-term borrowing costs to rise?

There is a lot of noise currently about UK government borrowing costs.The focus has been on what is known as the 30-year gilt yield, which is the effective interest rate of what it would cost the UK government to borrow money over three decades.This rate reached a 27-year high on Tuesday, which some argue is a verdict on economic mismanagement and fiscal credibility. The bond vigilantes are striking, and this is…