I think people are worried he'll be gone like Tristan and he will but in the third book All Things Wise and Wonderful, he is working on farm animals in various locations, looking back on Skeldale House, Helen and Darrowby. Sharing recollections just like he does in the other books. I could see how they could open each episode with him in some far flung village and he will see something that reminds him of a case he worked on or something he and Helen did and we will see the rest in flashback.