This is where, after you've applied, and you've ever farted upwind in a downwind breeze you'll have any and everything you may have forgotten/thought you'd paid off will return to haunt you.
Do you honestly believe Experian is there to help you realise why, say, curries turned you down for HP on a 4 pack of Duracells?
No, they are there to sell your details on to any and everybody who'll give them 10p (guess).
E.G. Owe Barclays £1000. They lose you. They get an insurance payout for £1000 and give up chasing you, meanwhile, sell the debt for £100. The new company chase you. Miss out, sell the debt on for £20. Take the £80 loss because the fella next door said YES!! I AM HERE!! I AM THE MESSIAH (OK maybe not the last bit!
). So the new company bought 2x £1000 debts for £200. One says "Fek Off" (because this sensible person knows the banks have covered their asses), meanwhile "The Messiah" pays his £1000 plus the £630.33 for the stamp/envelope/piece of A4 and ink, the company gets £1630.33 over a year, maybe two, for a £200 layout.
The bank has covered their arse. The debt collectors cover their arse, etc. etc. I can nearly guarantee that 10-15 years down the road your name will be sold on again on a "sucker list" by which time you'll have lost the receipt to clear A that you thought B had taken but you paid C but now D is on your case.
Experian are pishing themselves! You pay to see if you are clean. As soon as you contact they sell your details on to every mother and his dog who has a couple of heavies to make your life a misery.