 In 1989, Brohn began to collaborate with Cameron Mackintosh, orchestrating approximately ten of his shows also working on scores for musicals with Trevor Nunn and the Royal National Theatre, London.Additionally, Brohn has provided arrangements for Liza Minnelli (the complete orchestrations to her Minnelli on Minnelli tour, 1999–2000) Marilyn Horne, Renée Fleming, Frederica von Stade, Plácido Domingo and Jerry Hadley which have all been recorded.Brohn has also collaborated with conductors such as André Previn, John Williams and Keith Lockhart.