I have a filled column in worksheet_1 called "Reference". I have another
empty column in that worksheet, called "Data" that I want to populate with
values from worksheet_2.

Worksheet_2 has the necessary reference number to link to

My question is "how can I do a lookup on "Reference" in worksheet 1, pick up
the same reference number in worksheet 2 and then do the vlookup on that to
bring the correct data value over.

Thanks

Rob