Why has the credit card application been declined?

My partner has applied for 2 credit cards (egg and barclaycard) and has been declined for both of them. he has never had a credit card before but has had several loans and a mortgage which he has never missed a payment on. will the fact that he is never had a credit card have been held against him? now if he applies for another card, he has to tick the box that asks if he is been declined for a credit card before and that will work against him even more. he is 26 if that makes any difference.
Answer
My advice is for him to get a credit report asap (try experian or equifax). it may be that there is some bad debt outstanding in his name that he is unaware of, or that anybody else has been using his details...