The ceremony at 12.30pm will be directed by Hugh Wooldridge and has been arranged by Liz Robertson, Lerner's eighth and last wife ("I love women; I've got the bills to prove it," he said), who was 67 when he died, but spent five years married to Liz, after they met when she played Eliza in a West End revival of My Fair Lady in the mid 1970s.
Her Professor Higgins was Tony Britton, who is taking part in the ceremony along with his son, Jasper, Sally Ann Howes, Anthony Andrews and lyricists Tim Rice and Don Black. Andrew Lloyd Webber is expected to put in an appearance, too.
But not, probably, Stephen Sondheim, who was characteristically bitchy about Lerner in his recent book of collected lyrics "with attendant comments, principles, heresies, grudges, whines and anecdotes."
Sondheim opines that Lerner's lyrics lack energy, flavour, passion and personality, saying that he'd rather live with the second-best of Hart and Gershwin than with Lerner's best. But he also says that My Fair Lady, which he saw on its second preview in New Haven, is the most entertaining musical he's ever seen -- "exclusive of my own, of course."
Sondheim is completely wrong, but you can understand the temperamental aversion to a civilised stylist in one whose own songs are intricate word games tortured into self-consciously brilliant patterns and musical poems.
Lerner's collected lyrics are as enjoyable to read as Sondheim's, and easier to hear in the theatre. There are two more performances this Sunday of one of his flops, Coco, at the Lilian Baylis studio at Sadler's Wells, in Ian Marshall Fisher's Lost Musicals series, with Sara Kestelman and Edward Petherbridge leading the cast.
The music for Coco was written by Andre Previn, and the appearance of Katharine Hepburn in the title role of the great couturier (who led a totally unexciting life, hence the flop) ensured the largest box office advance in Broadway history when it opened in 1970.
Coco wasn't terrible, said Martin Gottfried; it was just a lobby. The Radio City Music Hall lobby, to be precise, on which Hepburn disported herself like an over-dressed chief usher. Coco Chanel was delighted they'd got Hepburn to play her; but she was expecting to see Audrey, not Katharine. They'd got the wrong one.
What I remember of Previn's music has a sort of desperate charm and ooh-la-la about it, but Lerner's lyrics are pretty good, full of Gilbertian zest and clever rhyming; even Sondheim would have to acknowledge, for instance, the deftness of Coco's hymn to material freedom: "All the pelf on the shelf is freedom. Clink clink they jingle. With money to pay, oh, debt, where's thy sting? So come, legal tender, be tender, surrender, And let freedom ring."
As the jazz musician and critic Benny Green pointed out in his fabulous introduction to Lerner's collected lyrics, he was, from start to finish, a dramatist who wrote part of his plays in rhyme. And in praising Lerner's obsessive attention to detail, and placing him in a top six ranking alongside Cole Porter, Lorenz Hart, Noel Coward, Ira Gershwin and Johnny Mercer (no, no Sondheim), Green declared that writing a lyric was, for Lerner, "a process so subtle, so intricate, so demanding, so severe in its exercise of the art of concision, that he was, on more than one occasion, known to have agonised for a week over a single line, and not always to his satisfaction."
This diligence and obsessiveness was masked in the apparent fluency of the end result, and Lerner himself would dismiss his work with a self-deprecatory wave of the hand, saying that what he did was akin to wood-carving or carpentry. He was right: you can see the detail but never the join.
Anyone who's given so much pleasure to so many through shows like Brigadoon, Paint Your Wagon, My Fair Lady, Gigi and Camelot deserves his place in the actors' church.
Even more fittingly, Liz will host an after-party reception in the Grand Saloon in the Theatre Royal, Drury Lane, scene of the famous first nights of both My Fair Lady and Camelot.
And, with regard to Camelot, here's another lyric Sondheim wouldn't like and couldn't write, it's so sexy and simple: "How to handle a woman? Mark me well, I will tell you, Sir: The way to handle a woman is to love her...simply love her...merely love her...love her...love her." Music and performance fill in the dots, but you have to write the dots, too.
Soon after they married, Liz fulfilled a cabaret date at the Ritz Hotel, singing a few of Lerner's songs (including a wistful ballad from another late flop, "Dance A Little Closer", which became generally known on Broadway, after the first night, as "Close A Little Faster").
There was an "element" (as Dame Edna used to say) in the audience that night, a table of rowdies who kicked up a storm of ignorant bolshiness through one of the quieter numbers. I protested angrily and was invited outside to prove my valour in no uncertain terms.
I managed to face the yobboes down and was later praised for my pains by Lerner himself. This was one of the great moments in my life, and I shall never forget his charm and good humour in thanking me for protecting his wife's virtue.
As I said to him at the time: what else could I do? We both grew up in Chadwell Heath in Essex, and her dad was a copper. Mine wasn't, but I've always had a highly developed sense of law and order in the theatre, and life is not just a cabaret, old chum, it's a test of sentiment and good behaviour.