What do you call a biographical play which is as unquestioning in its adoration of its star subject as it is blinded by self-obsessed camp homosexual fandom?

Is there a genre called fag-hagiography?  There is now.

For sure, like most tapettes d’un certain age, I loved Lucy. My sixties childhood was coloured by her black-and-white window into American situation comedy. I secretly wanted to live next door to Ethel Mertz, and for the brief time we had a house in Holland when I was 11 or 12, subtitled episodes of De Lucy Schouw taught me Dutch.

I can’t love I Loved Lucy quite so much. Author Lee Tannen was the son of Lucille Ball’s second husband’s sister’s husband’s cousin’s wife. As a tongue-tied child he’d been at extended family events with Ball but only in his thirties did he parlay an introduction into becoming her friend, backgammon partner, and confidant. The play refers to him as a writer but Wikipedia doesn’t throw up anything else he wrote and it’s hard to see why Ball chose him out of many thousands of sycophantic gay fans.

As America’s most famous and beloved comedienne, Sandra Dickinson does a tremendously good job with what she’s given: she looks and sounds convincingly like Ball, has the gaping smile and the sideways glance down pat, and treads a neat path between the powerful studio boss Ball became, and the guileless sitcom clown she once portrayed. Matthew Bunn is effectively sweet and gauche and needy as Lee, although some of his American phrasing is very slightly adrift.

Everything about Lucy is fascinating, but nothing about Lee is, which is the crux of the problem because the whole play is seen through his periscope of self-aggrandisement and his almost masturbatory delight at being in the same room with his icon. His urgency to be seen with Ball at as many galas as possible is odd: when we want to know what Bob Hope said and did at the Oscars, focusing on himself feels somewhere between pushy and downright uncomfortable.

There are some genuinely hilarious moments, mostly when Ball is wisecracking or denouncing other Hollywood legends, and the scene on the back lot of a movie studio where she almost stumbles on to Carole Lombard having her fanny waxed is epic.  Dickinson’s timing is so perfect, it could be Lucy herself telling it to Joan Rivers.

But so much is skirted around that you emerge frustrated at the gaping omissions – why weren’t her children involved in her later life, why didn’t her best friends Vivian Vance or Paula Stewart throw Lee out of her house long before he burrowed under her skin like a fey parasite? Why, if they maintained such a solid friendship over ten years, did multi-millionaire Ball leave Tannen only a second-hand car in her will?

Why does he appear to abandon a career and partner in New York to spend so much time in Hollywood where he wasn’t working? Why does Tannen appear to embrace Lucy as Jewish? She came from a Baptist family: she even married her second husband Gary Morton, a stand-up comic from the ‘Borscht Belt’ kosher resort circuit in upstate New York – in a Christian church.

From its initial 70-minute-no-interval 2010 version in Laguna Beach the piece has been extended by an hour, but even for the diminishing audience who can recall Lucy’s heyday it needs to revert to the original format, with more ruthless direction and a script doctor.  The danced ending, to ‘Hey, Look Me Over’ from Ball’s misjudged 1961 Broadway venture Wildcat is appalling.

The Ball/Arnaz estate is fiercely protective of its legacy: a touring stage production based on two episodes of the sitcom was unable to use the character names Lucille Ball and Desi Arnaz in its script, and such exigencies may have prevented Tannen from a more comprehensive telling.

Better news, folks, with the producing involvement of Ball’s children Lucie and Desi Jr., there’s to be a new movie of her life. With Cate Blanchett.