An examination of Michael Haydn's Missa Sancti Hieronymi, written to mark the 10th anniversary of the accession of his boss, Hieronymus Colloredo, to the archbishopric of Salzburg. It quickly became known as the 'Oboe Mass', on account of its highly unusual use of six oboes. Leopold Mozart was critical of what he regarded as Haydn's heavy drinking, but lavish in his praise of this impressive work, whose first performance he attended. The programme concludes with Haydn's Symphony in G, which until recently was thought to be by Wolfgang Mozart.