The Night Manager was the Beeb, or are you thinking of something else?
Martin Compston from The Ice Cream Girls was in In Plain Sight more recently; about a real-life 50s/60s serial killer in small-town Scotland. That was pretty good.
The Halcyon, about a fancy hotel before and during WW2. Bit like Downton in a hotel; drama among the folk from both upstairs and downstairs, as well as guests.
Grantchester, about a village vicar in the 50s who gets involved in solving crimes with the local police inspector. Kind of 'cosy crime' (nice vintage threads, lovely houses etc) but surprisingly keen to address more serious issues.
Ages ago, but Midwinter of the Spirit with Anna Maxwell Martin in the lead. Supernatural mystery. Quite atmospheric. Set in beautiful scenery (Herefordshire, I think.)