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.