Not sure on how the character would reply.

On one hand, he would not give the traitor his name so freely, let alone one who did not recognize him (although he has been rather reclusive to only be largely active in the UK, hence may explain the lack of recognition here).

Along the same line of logic, there is no need to fulfill such a request from a foe who had just recently been bested and humiliated the vampire kin not only in his betrayal and association with the humans, but also by falling in battle without having put up a significant battle. Thus it was unworthy of the younger to even know of his name, let alone speak it. 

On the other hand Lord Bedivere's pride may be outraged from the lack of recognition. Then he would go into a lengthy monologue amidst the battle as to who he was and how dare the knave not know him... 

Finally, Who did save him? This is a philosophical question of ideologies. To the elder, the vampire was not truly saved until he joined the proper side. Similarly, he could argue that whoever sired him was the vampire to be known as his savior from being human cattle. Then there was the question of Gabriel's influence which may have been involved due to the proximity of the vampire to the battle. And finally the creator of the Cure (which was formulated by Crowley after the human occultist borrowed certain texts from Lord Bedivere).