CELEBRATED daughter of Leeds Kay Mellor is so prolific that her premiere of Fat Friends, The Musical on familiar turf at the Grand Theatre coincides with her new BBC One drama Love, Lies And Records, filmed in her home city. As if she were not busy enough already, she has directed her debut musical too.

Mellor has always had a longing to pen lyrics and work with a composer, her programme note rveals, and a few years ago she was approached to write the book for a show that "will remain nameless". Initial excitement, however, made way for the realisation "the musical I actually wanted to write was Fat Friends".

Seventeen years on from its TV debut with Ruth Jones, Janet Dibley, Alison Steadman and Gaynor Faye, Mellor reactivates the characters of Kelly, Kevin, Betty, Fergus, Lauren, Val, Paul and Alan. "They were all still in my head, and I wanted to breathe life into them again, only this time with song," she reasoned.

Typically of Mellor, she takes to lyric writing like the proverbial canard to a lake, while Nick – son of Andrew – Lloyd Webber composes a highly proficient populist score but without his father's gift for a nagging hit tune.

The setting is Headingley today, represented by a row of shop frontages, such as Fergus's chippie and a wedding shop that opens out like a doll's house in Bretta Gerecke's design. The fish and chip prices are up to date, with comments from Kevin Kennedy's Fergus onf the difficulties faced by chippies as fast-food competition hots up, but overall, especially by comparison with Love, Lies And Records, it all feels somewhat retro and a tad soft, weakening Mellor's normally sharp sense of reality.

Kay Mellor, however, is a witty and wise maestro in the field of human emotions, vulnerabilities and vicissitudes, both male and female, and a musical is a natural progression because it further heightens her already heightened drama. It is often said that people burst into song when there is nowhere else left to express feelings, be it in opera or its more modern offshoot, the musical, and certainly that is the case here in a story that, in Mellor's words, takes in the themes of love, (weight) loss, jealousy, family and body image.

Broader in tone than her past work, it also takes in a Super Slimmers Group, a shop fire, a hen party, dodgy slimming pills, a will-they-or-won't-they-marry finale, and loads of Leeds blunt humour.

Jody Prenger, right up there with our best musical stars right now, is a joy as struggling slimmer Kelly, so determined to make the most of all the material, both in her wedding dress and her fabulous performance, full of personality, comic vitality and top-notch singing.

Andrew "Freddie" Flintoff is already an all-rounder beyond the cricket field with hit TV and radio shows and brief bash at boxing, and he now adds warm-toned solo and duet singing and big-hearted northern lad comic pathos to his repertoire, although not exactly comfortable movement, as hapless husband-to-be Kevin.

Like many "non-actors", Flintoff favours hands in pockets as his safety-first position, but by comparison with Ian Botham and Frank Bruno in bygone Bradford pantos, he is definitely in with a sporting chance of further stage engagements.

Sam Bailey's Betty is in good singing form too, although her role offers slim pickings, while Atomic Kitten Natasha Hamilton is suitably catty as cynical, scheming Scouse slimming club owner Julie Fleshman in the show's brashest performance.

The ladies of Leeds that inevitably dominate the audience lap it up, revelling in its Yorkshire familiarity and honesty, but Fat Friends, The Musical falls short of Mellor's best and weightier work, and the previous musical premiere at the Grand, Gary Barlow and Tim Firth's The Girls, was a cut above.

Fat Friends, The Musical, Leeds Grand Theatre, until December 2. Box office: 0844 848 2700 or at leedsgrandtheatre.com