“The Lady in the Van” is a wonderful film and a must-see. If you see it in an arthouse or independent movie theater, arrive early to get a seat. Call it the “Downton Abbey” effect.

“The Lady In The Van,” touted as “a mostly true story,” stars Maggie Smith (primetime Emmy recipient, 2011, ‘12, Violet Crawley, Dowager Countess of Grantham, “Downton Abbey,” 2010-’15) as Mary Shepherd, the “Lady” of the film’s title who parked her car in the London driveway of author Alan Bennett (Alex Jennings) one day and remained there for 15 years.

The film, directed with impish charm by Nicholas Hytner (“The History Boys,” 2006; “The Crucible,” 1996; “The Madness of King George,” 1994) is based on the screenplay, novella and play (1999) by Bennett (Oscar screenplay-nominated for his play, “The Madness of King George”; “The History Boys” play, 2006; Tony Award recipient, “Beyond the Fringe” comedy troupe and TV show (1964) with Peter Cook, Jonathan Miller and Dudley Moore.

Hytner, who directed the original stage play, uses a brilliant device in the film, which I’m reluctant to reveal as it might ruin your enjoyment of seeing the film with fresh eyes. Suffice it to say, the technique is not shown in previews for the film and is an absolute delight. Hytner has a lot to work with: great actors and brilliant dialogue (“In life, going downhill is an uphill climb.”).

Mary Shepherd’s real name was Margaret Fairchild (she died in 1989), a classical pianist who performed in a BBC Proms concert.

“The Lady in the Van” is a consideration of a life, that of the “Lady” of the title, as revealed through the eyes, voiceover, questions and writing of Bennett. The film also deals with an author’s lot in life, the contrast between fiction and reality; the contradictions thereof, and the responsibility (or not) of a writer to his or her subject.

Jennings (“The Queen,” 2006; “Babel,” 2006) is extraordinary as Bennett. Visually, his face has the bemusement of a Stan Laurel. His demeanor has the perspicuity of a Peter O’Toole. We hear, and see, him talk to himself with the understated authority of a David Niven. His is the perfect counterpoint to Maggie Smith.

Smith is remarkable as Shepherd. This is fearless role, even for Smith in her long and illustrious film career (“The Best Exotic Marigold Hotel,” 2011, and sequel; Professor Minerva McGonagall, ”Harry Potter” series; Oscar recipient, actress, “The Prime of Miss Jean Brodie,“ 1969; Oscar recipient, supporting actress, ”California Suite,” 1978; actress nomination: “Travels with My Aunt,” 1972; three supporting actress nominations: “Gosford Park,” 2001; “A Room with a View,” 1985; “Othello,” 1965).

Smith is aggressively disagreeable as Shepherd, yet manages to present us with a certain sweetness at the core of the character. We want to like her. She doesn’t want to be liked. Smith portrayed Shepherd in the original stage show and a 2009 BBC radio version. Since the film was released in January in the United States, Smith deserves to be nominated for yet another Oscar.

Jim Broadbent has a supporting role as a n’er do well. James Corden has a cameo as a street market vendor.

“The Lady In The Van” initially may drive you away. After you see it, you’ll wish you had known this “Lady” better. Don’t miss it.

“The Lady In The Van,”MPAA Rated PG-13 (Parents Strongly Cautioned. Some Material May Be Inappropriate For Children Under 13.) for a brief unsettling image; Genre: Biography, Comedy, Drama; Run Time: 1 hr., 44 min.; Distributed by TriStar-Sony Classics.

Credit Readers Anonymous:“The Lady In The Van” was filmed in Gloucester Crescent, Camden Town, London, England, at the actual house and street where the van in which Mary Shepherd lived was parked.

Box Office,Feb. 26: “Deadpool” made it a “threepeat,” continuing at No. 1 with $31.5 million, $285.6 million, three weeks, keeping “Gods of Egypt” opening at No. 2, with $14 million, as “Kung Fu Panda 3” dropped to No. 3, with $9 million, $128.4 million, five weeks, “Risen” continued right behind at No. 4, with $7 million, $22.7 million, two weeks, and “Eddie the Eagle” opened at No. 5 with $6.3 million and “Triple 9” opened at No. 6 with $6.1 million; 7. “How to Be Single,” $5.2 million, $39.6 million, three weeks; 8. “The Witch,” $5 million, $16.6 million, two weeks; 9. “Race,” $4.2 million, $13.8 million, two weeks; 10. “The Revenant,” $3.8 million, $170.5 million, 10 weeks

Unreel,March 4:

“Zootopia,”PG: Byron Howard, Rich Moore and Jared Bush direct the voice talents of Ginnifer Goodwin, Jason Bateman, Idris Elba and Jenny Slate in the animation film comedy about a city of anthropomorphic animals.

“London Has Fallen,”R: Babak Najafi directs Gerard Butler, Morgan Freeman, Charlotte Riley and Angela Bassett in an action-thriller about a plot to assassinate world leaders in London.

“Whiskey Tango Foxtrot,”R: Glenn Ficarra and John Requa directs Margot Robbie, Nicholas Braun, Tina Fey and Billy Bob Thornton in a comedy about a female journalist in war-torn Afghanistan and Pakistan.

“Knight of Cups,”R: Terrence Malick directs Christian Bale, Cate Blanchett, Natalie Portman and Brian Dennehy in a drama about a man reflecting on his relationships.

Four Popcorn Boxes out of Five Popcorn Boxes