Minnie the Magic Piano was a prop created for the original production of the musical Salad Days by Julian Slade and Dorothy Reynolds. It opened at the Bristol Old Vic in 1954 and transferred to London's Vaudeville Theatre where it ran from 5 August 1954 for over 2,000 performances. The magic piano is central to the plot, in which a tramp's piano makes anyone who hears it play, dance. Minnie was extremely well used, spending five and a half years at the Vaudeville, followed by two years on tour.

Since Salad Days was written hastily to fill a gap in the schedule at the Bristol Old Vic, there were only two and a half weeks for rehearsal and preparations. The first version of Minnie was assembled by the master carpenter Phillip Wilson and his assistant Tom Lovell from parts of old pianos mounted on pram wheels. Dorothy Reynolds was upset because it was too large, the size of an upright with a full keyboard. It needed to be small, or 'mini', with a five and a half octave keyboard, so Tom Lovell built a second version under the supervision of Patrick Robertson, the production designer. Having lost it to the cast for rehearsals as soon as it was built, there was a huge rush to get it finished in time. In all, thirteen people helped create it, painting it, making the lamps, finding the fringing and pasting the back with theatrical prints. Salad Days inspired the theatrical ambitions of the young Cameron Mackintosh, the international producer of musicals, and Minnie remains an important symbol to him of his early love of musical theatre.