GoogleSheets: List all all values that occur at least once

Hi,

Looking to list all values in a columns that appear at least once in a column. I have 200 lines, with circa 100 different building codes. eg LON001, LON001 PAR001 etc. I have some buildings with only one line, but I have multiple buildings with multiple lines dependant on the number of utility meters. I am trying to pull together a list of all the building codes.

I can copy the column and remove duplicates, but over time I will be adding more and more lines and more and more building codes so I would like (if possible) for the list to automatically identify a list of building codes.

Any ideas?

All help is massively appreciated.

Works a treat - Thank you!