(Reuters) - Doorstep lender Provident Financial Plc said on Wednesday tighter underwriting rules led to a drop in business volumes in April, while adding that it saw signs of a modest recovery in May.The company, which provides credit to people who do not meet the lending criteria of mainstream banks, said loans to existing consumer credit division (CCD) customers are currently at just one-third of the expected volumes. Provident set out to return CCD to profitability, after successfully..