Hello Mr. Cornwell

I have a question about the difference between Derfel’s age and Arthur’s. I thought Arthur was at least 10 years older , but in the second book , Derfel says that Arthur has 30 years old , and a few pages later, in a conversation between both, Arthur reveals that Derfel has nearly 30 years. It’s take me confused about the real age of Derfel.

I know you wrote this books a long time ago, but I began to read it a few days ago, and I’m really enjoying it !

Gustavo Paixão