SOLVED! Looking for British countryside crime drama @2000

Separate Lies, 2006, Tom Wilkinson and Emily Mortimer

Married couple, wealthy, English countryside, opulent home.  Someone in neighborhood is run over by a car and killed while they are having a garden party, I believe, no suspects.  Wife is played by actress like Penelope Wilton.  Thought it was she, but can’t find the movie.  Thought husband was played by Tom Wilkinson, struck out again!  Husband/brother/brother-in-in-law is the culprit?  Would love to see this movie again. Early 2000’s, best guess, maybe later, contemporary time frame.  Movie, not TV series.