Did they make an unsecured loan of up to £15,000 at 4.8% then ? I find that very hard to believe. People are paying mortgage rates at or above that.
Quite a few providers have rates similar to this. However a point to bear in mind generally, is that these rates require a squeaky clean credit history with a score to match. That also applies to anyone with a financial association to the primary applicant. Mortgage rates (secured loans) are typically running at variable margins of 3.5% above base rates, with promotional fixed rates as low as 2%. As with any rate, the credit score is usually the determining factor.
Another point to be aware of, is that a quote doesn't constitute an offer It is provisional and dependent. An application needs to be made before the terms (including rate) are offered (or not.) Any credit application (whether accepted or not) leaves a footprint on your credit history which is likely to have a short term negative effect on an individuals credit score.