Lionel Bart used Dickens' Oliver Twist for his hit when penning Oliver! And Andrew Lloyd Webber looked to France and writer Gaston Leroux for his Phantom of the Opera.
In fact ALW used the written word before when no less a title than The Bible was used as inspiration for his first two big hits - Joseph and his amazing tecnicolor dreamcoat and Jesus Christ Superstar.
Then came Claude-Michel Schönberg and Alain Boublil with their take on Victor Hugo's 1862 novel, Les Miserables.
Of course this literary leaning all came to an end when shows like Notre-Dame de Paris and The Man in the Iron Mask proved that not all that is written can be made into gold! Although Notre Dame de Paris did well outside of London even Andrew Lloyd Webber's own Musical adaptation of Wilkie Collins' The Woman in White couldn't buck the trend.
Then it was the turn of the Juke Box musical - Buddy, We Will Rock You, Dreamboats and Petticoats, Mamma Mia.
But that trend's Waterloo seems to be coming with Backbeat and Desperately Seeking Susan: not bad shows, but not the money-spinners they once might have been.
I wonder what will happen to the Green Day and Spice Girl musicals coming to town next year? So the next source of inspiration became the movies.
It was probably Disney that started the trend with a whole bunch of films that were pretty much musicals anyway with The Lion King being the most successful in London.
But this obviously started the West End thinking! So now we have no less than five stage musicals based on smash hit films.
But these are no lazy copies.
To make a successful musical of a successful film you have to make the audience forget the successful film.
And the only way you can do that is by being better than the audience's expectations - and good theatre can do that.
The theatricality of The Lion King is very different to the theatricality of Billy Elliot but both adaptations bring to the piece something that the film cannot.
Both work on the interaction between cast and audience and both come out better because of that.
So Billy Elliot - the musical (they all have "-the musical" after their title to tell the difference) is not just the film with songs in, it looks and feels like it was written for the stage.
So what will you have seen in a cinema that, this winter, you can now see on the stage? Billy Elliot - The Musical Miners and ballet dancers, striking and tap dancing.
Awesome performances from the boys, made even greater by the fact that you know they are doing it night after night - for real! Legally Blonde - The Musical OMG they totally did it.
And like the film, this chick-musical is unaccountably enjoyed by men too! Ghost - The Musical Yes, the Demi Moore, Patrick Swayze, Pottery Wheel film opened this year and is up for awards this winter too! Shrek - The Musical The big green ogre is just as lovable on stage.
Out of the five shows it is probably most dependent on some great performances from its cast.
Priscilla Queen of the Desert - The Musical Although this is a film musical this is also a jukebox musical.
But who cares - it is great fun - if not a little over the top.
Closes on New Year's Eve - what a party that will be.
So, yes, you could see the film versions of these shows in your living room at home, but, as my science teacher once told me, "its like eating a toffee with the wrapper on".
Although I don't think she was talking about musicals at the time!