Musicals have always been a ­powerful currency in theatre, but this autumn’s London season is packed with song-and-dance shows even by recent standards. Both halves of the most bankable English musical-writing duo have separate new works – Tim Rice’s From Here to Eternity opened recently and Andrew Lloyd Webber’s Stephen Ward starts in December. In addition, two long-anticipated projects opened in the same week in London.Neatly, The Light Princess and The Commitments come from contrasting forms of theatrical funding – the subsidised National Theatre and the commercial West End, respectively – and also represent the two main ways of creating a musical: the former is written and composed from scratch, while the ­latter extends the currently domina