Did they make an unsecured loan of up to £15,000 at 4.8% then
Yep, they certainly did.
I originally had a loan from them at around 5.8% APR, paid around half of this off then contacted them to borrow more and consolidate some other stuff, and they offered me £15,000 at 4.8% APR. I couldn't find better on the market, so basically bit their hand off.
For the original loan, just a credit check, no security or evidence of anything. I've never missed a payment in my life, so they seem happy for me to borrow more, although £15,000 is their limit for an unsecured loan.