Hipster: Why did I get turned down?
No idea. Only V12 know the reason. Was this for a retail purchase?
First of all every lender calculates their own "score" using the application data and data obtained from the credit search. However given the Experian "score" and the small amount of the credit I would suspect affordability is not the issue other than you requested quite a small sum which most people would have put on a card.
This is more likely to be down to something not quite right either with the address format or electoral roll address format recorded on your Experian file compared with the address format used on the application, or even a typo with your personal details such as date of birth when the store put the application through.
Would be useful to obtain your Experian Credit Report not your "score" (which IMHO is a waste of time and money), and verify that a credit search was actually done.