For the first time in half-a-century, there is a major new production of Funny Girl on the London stage. At present, it's at a small theatre south of the river; in April it moves to the West End.

It stars Sheridan Smith and has had enthusiastic reviews. But there is a problem, perfectly expressed by the self-contradictory headline on the Observer's review: "Sheridan Smith makes Streisand's role her own."

No doubt Sheridan Smith is wonderful - she always is. But she cannot possibly make Streisand's role her own because we all know that it's owned by Barbra Streisand. Funny Girl and Barbra Streisand are as one. Not only did she define it, it defined her.

As everybody is (or at least should be) aware, it's the story of Fanny Brice, a New York Jewish girl from a poor background, talented, funny of course, certainly not conventionally good looking, headstrong but emotionally vulnerable, and with remarkable star quality.

By the time she was 20, she was headlining the Ziegfeld Follies. Barbra Streisand was a New York Jewish girl from even poorer circumstances (her father had died when she was one year old); she was talented, funny of course, headstrong, emotionally vulnerable and with remarkable star quality.

At 19, she was already a hit, playing gawky and sour-faced, as the put-upon secretary Miss Marmelstein in the musical, I Can Get It For You Wholesale. Two years later, she was the toast of Broadway playing Fanny Brice.

"She has everything that I will call a star," said Sophie Tucker, Brice's contemporary, "she is star material from now on. Nothing will stop Barbra Streisand".

"Some stars merely brighten up a marquee; Barbra Streisand sets an entire theatre ablaze," wrote Time magazine. "Actress, songstress, dancer, comedienne, mimic, clown - she is the theatre's new girl for all seasons." Two weeks before her 22nd birthday, she was on Time's cover.

"Now that I'm supposed to be a success," said Barbra, "I'm worried about the responsibility. People will no longer be coming to see a new talent they've heard about. I now have to line up to their concept of a great success. I'm not the underdog, the homely kid from Brooklyn they can root for any more. I'm fair game." So far, so very Jewish. Come to think of it, explain this: if it's completely out of order nowadays for a white man to play Othello, why is it okay for a gentile to play Fania Borach (Fanny Brice's birth name)? Charlton Heston played Moses (that was a long time ago), Mel Gibson played Jesus (God help us!). Can we expect to see Hugh Grant as Tevye the Milkman?

Barbra Streisand "the underdog" has had the last half-century being the overdog. Her mélange of insecurity and perfectionism, creativity and control freakery is legendary. ''Jewish American Princess'' doesn't come close, Jewish American Empress would still fall short; she's the diva of divas. She's also the star of stars, the only woman among the 10 best-selling recording artists of all time.

For me and others of Streisand's generation, who saw her from the start, her impact had few equals. You don't have to be pensionable to be moved by her but if you were around when her first LP - The Barbra Streisand Album - was released in 1963, and you had the ears to hear, you could not but be amazed. Harold Arlen's song A Sleepin' Bee was her favourite track. In her hands, it truly was a miracle. It is wrong to say "you had to be there" but if you were among the hundreds of thousands who saw her in Funny Girl on stage or the many millions who know the film, especially when it was new or newish, Streisand was defined for ever. If you came across her later, in mid-career, you were deprived of the shock of discovery and the sensational Funny Girl moment.

It may seem obtuse to say it about someone who is still one of the greatest megastars but Barbra Streisand was born a few decades too late. She is a year younger than Bob Dylan and two months older than Paul McCartney, geniuses of contemporary culture. But Streisand, despite her political activities, is not a modern person. You may, for example, want to hear her attempts at singing rock songs but I hope you never hear her attempts at David Bowie's Life on Mars; her version of Laura Nyro's Stoney End was bad enough.

Watch Streisand in Funny Girl and you realise that, if she'd been in movies in the 1930s and '40s, she would have left every other female musical star for dead. In 1969, she won the Best Actress Oscar for Funny Girl but shared the award with Katharine Hepburn who won hers for A Lion In Winter.

As it happens, Streisand's second best film is Peter Bogdanovich's What's Up Doc? the very funny 1972 pastiche of Hepburn's 1938 screwball comedy, Bringing Up Baby.

Fanny Brice made her stage debut aged 13 at a music hall in Brooklyn. At 13, Barbra was at Erasmus High School in Brooklyn whose alumni include illuminati of all sorts. When she was 16, she apparently had a crush on fellow student Bobby Fischer; she sang in the choral club with Neil Diamond.

At the 1980 Grammy awards Diamond and Streisand sang his song You Don't Bring Me Flowers together. It's schmaltzy and utterly fabulous and their fondness for each other is there for all to see. Brooklyn, Brice, Barbra.

Funny Girl with Sheridan Smith is a hot ticket. She was brilliant in the musical of Legally Blonde, marvellous as Cilla Black on television, superb as Hedda Gabler. She's 34 and already an OBE. She was born in Lincolnshire.

She can do almost anything, including Funny Girl - but she can't make Streisand's role her own.

For more information on 'Funny Girl The Musical' at the Savoy theatre, call 0844 871 7687 or visit:

www.funnygirlthemusical.co.uk