The show is from the 1950s, but meant to recall the musicals of the 20s, especially "The Girl Friend." Linguistic note, that girl friend and boy friend were written as two words because the accent was on the second word of the phrase through the 20s. It is uncertain when the backshift of accent to say BOY-friend first happened, but it is heard often by WWII, and is consistently written as one word by that point.
The old roue Lord Brockhurst is comic relief in a show that is already light. It all comes right in the end, as the unacceptable poor boy the heroine has fallen in love with turns out to be the long-lost son of Lord and Lady Brockhurst after all.
This might be a high school production, which would be impressive. I heard years ago that the show is fun to do and inexpensive, and thus still common in high schools. An added plus is that it has many more roles for girls, which can be hard to find.