Power Query - Merge based on Bands

[AllisterB]

Hi

I have a master table that sets out bands and a regional code for each band. The Master also has specific mappings for specific codes.

Where there is not an exact match I wish to merge based on a band. Where there is an exact match I wish to use the specific mapping contained in the Master table.

My scenario is set out in the attached file.

I am open to ideas as to how to do this - A conditional column seems laborious - are there other options?

Thank You

Allister