In order to make ends meet, Lady Hadwell and her daughters, the ladies Penelope, Fiona and Charlotte who are the inhabitants of the stately Hadwell Hall, run it, with the help of their lively, young manager Joe Studholme, as a commercial enterprise with attractions ranging from a fun fair to all-in-wrestling.
The season is open, and the public arrive in droves to look over The Most Ancestral Home Of All. Penelope and Fiona, all legs and cut-glass accents, act as guides, but tomboy 'Charlie' keeps herself busy looking after the cars in the Veteran Car museum. Her sisters tease her over her grease-smudged appearance, warning her that 'the chaps' will never fancy her, but Charlie has her own ideas about love - when the right man comes along Bells Will Ring. One who would like to be that right man is Joe, who can sing his love for Charlie Girl, but can't tell her of it to her face. His reticence seems likely to be fatal when Lady Hadwell's old chorus-line comrade, Kay Connor arrives, bringing with her son Jack. One look, and Charlie is declaring I Love Him, I Love Him. Mrs. Connor wants Jack to marry a nice titled English girl, but he has no intention of getting hooked and says so - What Would I Get From Being Married? His mother does not give up easily - she has set her eyes on one of the Hadwell girls - her family could do with their 'class', and the Hadwell's could do with the Connor's money. She and Lady Hadwell agree Let's Do A Deal, as they reminisce over their days in the chorus together.
Joe still can't bring himself to speak of his love to Charlie, although he confesses to the furniture that MY Favourite Occupation is just being with her - but he has another problem. He has won a considerable amount of money on the football pools. This is only a problem because he won't take the money: he thinks that if he were rich Charlie would feel obliged to marry him for her family's sake. Pools man Nicholas has the publicity ready to roll, but agrees to hold back for a week if he can stay that time at Hadwell where he has fallen for lady Fiona. To pass unnoticed he disguises himself as a butler.
Lady Hadwell has arranged a ball in honour of the Connors' visit; Jack preens himself before the mirror, considering his own charm with the query What's The Magic, and Charlie eats her heart out because she hasn't got a dress to wear. Joe promises to find her one, and the first act ends as Lady Hadwell descends the staircase to be led by an escort of young men to take up her hostess' place amid the fountains and fairylights of the gardens of Hadwell Hall (When I Hear Music, I Dance).
The party has begun and Charlie still has no dress. Upset, she blames Joe for raising her hopes, and he in turn condemns Wainwright declaring I 'Ates Money. But money has been able to hire a beautiful dress from a film company. It arrives at last and Charlie is transformed from a grubby urchin into a veritable Cinderella as she waltzes off to the ball to the strains of the Charlie Girl Waltz, there to find Mrs Connor being the life and soul of, what she proclaims is The Party Of A Lifetime. Jack is very struck by the new Charlie and lures her into the summerhouse to press his intentions on her. She is cautious but delighted. This is Like Love! but when he kisses her no bells ring, and she runs out distressed, leaving her Prince Charming bewildered at the seeming loss of his powers (That's It).
Back at the party Lady Hadwell indulges in a surreptitious but lively dance with Jack's valet, Washington while Joe feeds the guests on Fish And Chips until midnight comes and it is time for Charlie's dress to go back to its hire shop. Undismayed, Charlie simply takes it off and carries on as if nothing had happened, clad only in her underwear. The other girls whoop with delight and follow the new 'fashion' until the dance takes on quite a new look in the Society Twist.
Joe decides that he can't face life near Charlie or without Charlie. He tells Lady Hadwell that he will have to leave her employ, but she encourages him - You Never Know What You Can Do Until You Try - to 'have a go, Joe'. His courage fails him, but when Charlie kisses him goodbye - bells ring! Charlie has found her own true love, Lady Penelope, in her underskirt, has captured Jack's attentions, and Wainwright has finally cornered the Lady Fiona. The result is that all Lady Hadwell's daughters are now off her hands at one 'Absolutely flippin' marvellous' go.