Is it a 'trick' question? As far as I am aware ALL our notes are made from the same - a cotton based paper so I'm not sure why �5 has been singled out.
Sorry delayed answer, just got in! Thank you all for ideas, not sure about three ages of Man as I thought it was seven ages, but will double check. Will possibly email royal mint as it is intriguing, have googled every possible combination to try and find answer!! Thanks again all.