“For the best fixed rates,” was once an advertising slogan used by a major UK bank. It was perhaps one of the most iconic, and indeed ironic, banking billboard slogans that became synonymous with the Libor rate-rigging scandal.

It is hard to believe that four years have passed since discovering that some of the UK’s biggest banks were deliberately altering measures of interbank lending rates to make a quick buck. After much debate since about a suitable replacement, it’s easy to see why the Bank of England has finally decided on the Sterling Overnight Index Average, known as Sonia.