Zopa link up with a credit company that appears to specialise in lower credit people.  If Zopa declines the borrower, and they choose to accept, they will be referred.

…..  However, due to strict criteria Zopa declines many applicants, who are then in need of a provider more suited to their circumstances. All unsecured loan leads distributed through paaleads.com will have actively asked to be contacted to receive advice on the wider market, and will be supplied to the adviser no more than an hour after the customer has been declined, ensuring the lead is active, and the customer is expecting the broker to call.

Source: Mortgage Solutions – Paaleads.com adds unsecured loan leads