LONDON — “Mamma Mia!” has been mumbling about an April 6, 2004, reopening at the Prince of Wales Theater — unless, of course, business remains so extraordinary at its current home, the Prince Edward, that everyone involved decides not to make the move to a smaller house (1,100 seats as opposed to 1,600).The cause for the transfer: The 2004 date marks the fifth birthday of the Abba extravaganza, which would benefit from the attention given to a shift in venue — and a newly automated set to bring the London production in line with those elsewhere. What’s more, the Prince of Wales by then will have undergone a $10.5 million renovation, which should make it among London’s swankier venues, as well as one of the ones with the best door trade. The cause against the move: “Mamma Mia!’s” London advance remains in the vicinity of $6.5 million — “You can set your clock by it,” says one insider — which represents pretty serious change. And if business remains that brisk, why risk a move, especially since the Prince Edward has no musical incumbent yet confirmed to take “Mamma Mia!’s” place? (The leading candidate has long been “The Producers,” but a London stand is not yet definite.) If the move does happen, the Abba songfest will end up at the theater that was producer Judy Craymer’s first choice all those years ago, back in the days when the theater was being earmarked for a potential commercial London transfer of the Sam Mendes “Cabaret” (which never happened). And before “Mamma Mia!” had become an international world-beater grossing $400 million-plus so far. A Brit heads west Rehearsals have begun for David Edgar’s “Continental Divide,” marking the sort of American world preem for a British dramatist that the theater rarely sees. While Britain premieres one American play after another (from “Glengarry Glen Ross” back in 1983 to “Take Me Out” this past summer), rare is the British work to be seen first in the States — as will happen March 1 when Edgar’s interlinked plays, “Daughters of the Revolution” and “Mothers Against,” open back-to-back at the Oregon Shakespeare Festival. “Continental Divide,” to use the banner title for the two plays, is a co-production between the Ashland, Ore., fest and the Berkeley Repertory Theater, two venues that, says Edgar, “independently asked me to write a new play for them.” In response, he proposed a joint project that follows the same gubernatorial election from opposing political camps — the Republicans in “Mothers Against” and the Democrats in “Daughters of the American Revolution.” Back in Britain, Edgar, who is 55 next month, is best known as the Tony-winning adapter of “The Life and Adventures of Nicholas Nickleby,” not to mention such politically themed works as “Maydays,” “Pentecost,” and “The Jail Diary of Albie Sachs.” But this time out, he says, the aim was to get “as near as possible to the kind of play I might have written had I been an American writer writing about American politics.” In other words, he notes wryly, “to try and write a great American play.” No accounting for… There’s no accounting — dare one say, as usual — for the judgment of the Olivier Awards panel, whose 2003 nominations would raise eyebrows in a theater capital more intensely attuned to such things. (Instead, one producer whose well-reviewed import went totally unnoticed summed up the prevailing West End sentiment toward the event, inquiring of me, “You don’t take these things seriously, do you?”) Well, maybe I shouldn’t, but c’mon: How can you nominate Trevor Nunn’s revival of “Anything Goes” for best musical production and not name a single one of its supreme supporting cast? Or omit “The Full Monty’s” London lead, Jarrod Emick, whose perf easily surpassed all but one (“My Fair Lady’s” Alex Jennings) of the men in the best actor in a musical lineup? In several cases, choices were made that seemed not just ill-judged but also unkind. Was Michael Gambon really preferable to his astonishing co-star Daniel Craig in “A Number,” the Caryl Churchill play — already an Evening Standard Award winner — that was itself bypassed in the lineup for best play? And it seems criminal to honor three of the four principals (Mark Strong, Emily Watson, Simon Russell Beale) of the Sam Mendes “Vanya”/”Twelfth Night” double bill and not Helen McCrory, whose unusually proactive (and beautiful) Yelena was arguably the best reviewed single performance of the two plays’ sellout London season last fall. Oh well, there’s always next year.