From IMDB:

A Cambridgeshire clergyman finds himself investigating a series of mysterious wrongdoings in his small village of Grantchester.

Currently we can see this  British TV Series on PBS. There are seasons for 2015,2016,and (in the future) 2017. For a really good summary see the Wikipedia discussion. My best reason for recommending this detective series is that despite there being murders, the atmosphere is gentile and pleasant.

All the episodes revolve around the two main characters Sidney Chambers (the priest played by James Norton) and Geordie Keating (the detective played by Robson Green).  Sidney’s guide is his religion whereas Geordie is guided by his hard-bitten cynicism. Sidney and Geordie complement each other, work together well, but are often ethically at odds.

As astounding as it may seem, James Norton also starred in the wonderful but grim British TV series “Happy Valley” where he portrayed the warped, evil, and vengeful Tommy Lee Royce.  Sidney Chambers is as appealing as Tommy Lee Royce is repellant. If you are into “grim but great”, then do NOT miss “[Un]Happy Valley”.

Robson Green is also worth watching in the TV series “Wire in the Blood” in which he is a psychologist who gets inside of the minds of both killers and victims to aid the police in solving gruesome serial killings in Northern England. Be careful, however, because the first episode in that series is a bit ugly.

Again Robson Green is worth watching in the TV series “Touching Evil“, another twisted and gritty series in which he was brought back to life through the miracle of medicine, now walking a tightrope on the edge of sanity as the semi-suicidal detective hunts down serial killers and other perps through his gift for thinking like they do.

In summary “Grantchester” is  civilized whereas so many other British detective series can be grueling to watch.