Hi @scotttwhy,
What @ipazin has provided is clearly the solution to your specific problem and as you can see, Column Rename (Regex) is a really useful node for these situations. Regex has many uses in KNIME and elsewhere, and I can recommend the regex101.com site for trying out and exploring regex.
Another useful site is rexegg.com, along with Regex Cheat Sheet
As you mentioned transposing tables to modify the column headers, I thought I’d also add some further information on how you can modify the column names using table transposition and various transformation nodes, which could be adapted for situations where regex rename alone would not be sufficient.
Change column header date format.knwf (18.2 KB)
btw the “Transpose” node in KNIME 4.x becomes the “Table Transposer” node in KNIME 5.1
NB. Please don’t additionally try to mark this response as the solution though, even if it works 
as only one answer can be a solution on a thread, and I think that @ipazin’s answer is the best solution for your question.