I too have been used to seeing Roy Marsden as Adam Dalgleish, but changes are not always bad. I watched it on PBS recently, so it was some years after it first appeared in the UK. It was one of those "I know that person" moments that often occur while watching British programs. More recently here we have watched Mr. Shaw in the Inspector George Gently series, and here he is looking much younger! The production dates explained that confusion.
I have enjoyed the two programs very much. I hope there are more. My only problem is that "Death in Holy Orders" ran for three hours from 8-11 pm. I just can't stay awake that long! A friend in the UK explained that their version is cut up into shorter episodes, perhaps hourly. This is a PBS choice, and doesn't take away from the whole production.
Such a nice change from continuous gun battles and car chases!