Almost every Hollywood movie of “the war years” was an embarrasment of riches when it came to European expats decorating the cast. “Casablanca” was practically a make-work project for conflict refugees. British films with a patriotic bent — “The 49th Parallel,” for instance — were often filled with famous faces in small roles, getting across the idea that everyone was “doing our bit” to fight fascism.

But none of them, not even “Stage Door Canteen,” surpassed “Forever and a Day” for “Hey, isn’t that?” character actor delights. For a film buff, it’s a must-see movie, just for the parlor game pleasures it provides.

A cast of dozens and dozens, with seven directors, twenty-one credited screenwriters (Hitchcock allegedly wrote some of it, uncredited) make this must-see-cinema for anybody still playing “Six Degrees of Kevin Bacon.”

The story is simple enough, but downright soap operatic in all its characters and complications. An American with the poncy name of Gates Trimble Pomfret (Kent Smith) in London during The Blitz of 1940-41 has to deal with some old family property before rushing home.

“If I’m going to have to eat shells and shrapnel, I’m going to do it on my own country’s dime,” he says, cynically leaning into his homeland’s neutrality.

The property is an historic house in a city of such houses, this one built in 1804. A British woman renting it, Lesley Trimble (Ruth Warrick) wants to buy it,”for sentimental reasons,” she says. And for cheap. As he’s of a mind that this place isn’t long for this world, given all the bombing, he’ll hear her out.

The basement is an air raid shelter, filled with make-a-brave-face sing-alongs, led by a priest played by Herbert Marshall. Future TV icon June Lockhart appears as a teen in the air raid shelter, the last surviving member of the cast (as of this writing).

Upstairs, “serving tea in the middle of an air raid,” Miss Trimble tells the flirtatous Yank, whose middle name suggests “We might be related,” the story of this great house, which was built, a bronze plaque tells us, by Sir Eustace Trimble in 1804.

In four chapters, we’re taken back to the Napoleonic Wars, the early reign and last years of Queen Victoria and World War I, showing us Britain and the house under threat from Napoleon and external enemies, and changing times within.

C. Aubrey Smith plays the elderly Admiral Trimble who built the place, out in the country on the edge of London as “the Corsican” (Bonaparte) threatened Britain with invasion. He quotes this “young” poet, that “Wordsworth” fellow, about the need to defend this house and this land from authoritarian invasion.

“We must be free or die, who speak the tongue. That Shakespeare spake!”

The admiral’s son (Ray Milland), a Lieutenant, gets mixed up in efforts to marry a young woman (Anna Neagle) off to some rich older man (Claud Allister) by her guardian, the oily Ambrose Pomfret (Claude Rains, a grand villain). For the first time, the house must literally be defended from invading ruffians.

And the Pomfret family and Trimble family are thus forever bound by the house. A member can marry a brassy Cockney maid (Ida Lupino) and run off to America, but the connection remains.

We’ll see fortunes made as a family member is talked into manufacturing cast iron bathtubs (Buster Keaton is a silent plumber doing the installing). Snide servants (Charles Laughton) and monied aristocrats (Edward Everett Horton) will reside there, celebrating Queen Victoria, attempting to master the horseless carriage (early motorcars), hosting American servicemen (Robert Cummings) during The Great War (WWI).

Warrick’s Miss Trimble, as she narrates, notes that these were “all people I should like to have known,” these generations who sat in gardens (long gone) and note “Our gardens are worth fighting for.”

The idea of the film, which survived many rewrites, delays in production and much editing to try and keep up with WWII history as it was happening, was to bolster the ties that bind Britain and America.

“Forever and a Day” is quaint and sentimental and old fashioned, but the players often sparkle, with the lighter moments having a timelessness that still plays.

Poor Susan (Neagle), defended by this gallant stranger in uniform (Milland), lies that they’re to be married to get her guardian (Rains) off their case. Milland’s way with a droll comeback to a woman who “just proposed to me” is perfectly pitched.

“I insist that you make an honest man out of me.”

Laughton is EveryServant whoever looked down on his “betters.” Lupino makes quite the Cockney spitfire, with Victor McLlaglen cheerily hailing cabs as a doorman and many other famous faces and voices turning up as air raid wardens, cabbies, later relatives, dinner guests, servants or bomb shelter refugees.

Future “Miracle on 34th Street” Santa Edmund Gwenn twinkles, Marshall, Ian Hunter, Una O’Connor and Montagu Love from Warner Bros. “The Adventures of Robin Hood” turn up, Richard Haydn is here, years before “The Sound of Music,” Nigel Bruce takes a leave from his Dr. Watson duties with Sherlock Holmes for a scene, Elsa Lanchester, like her husband Laughton, plays a servant and Merle Oberon glamorizes the whole enterprise just in scene or two.

Viewed today, what stands out is how much the movie hides its piecework production history and plays as a through narrative. But its real value is as an artifact, a sentimental, unifying remembrance of the “finest hour” which “Forever and a Day” reminds us, wasn’t just celebrated on the other side of the Atlantic.

Rating: “approved”

Cast: Ruth Warrick, Ray Milland, Kent Smith, Ida Lupino, Merle Oberon, Victor McLaglen, Buster Keaton, May Whitty, Robert Cummings, Edward Everett Horton, Charles Laughton, Anna Lee, Claude Rains, many others.

Credits: Edmund Goulding, Robert Stevenson, Rene Claire, Cedrick Hardwicke, Frank Lloyd, Herbert Wilcox and Victor Saville, scripted by C.S. Forester, Christopher Isherwood, Donald Ogden Stewart, Claudine West, Norman Corwin, James Hilton, R.C. Sheriff, Gene Lockhart, Emmet Lavery, Lawrence Hazzard, Jack Hartfield, Peter Godfrey, Charles Bennett, John Van Drueten, Alice Duer Miller, Frederic Lonsdale, Michel Hogan, W.P. Lipscomb, Sid Herzig, Alan Campbell and KeithWinter. An RKO/Cohen Media Group release on Tubi, Amazon, etc.

Running time: 1:46