To succeed in the musical world of the 18th century, you had to be ready to travel. The life led by composers, singers and instrumentalists was a kind of cultural nomadism, with nowhere counting as home for long and an existence dominated by continued journeying in rickety coaches over atrocious roads, with no firm guarantee of fame and profit at your final destination. Sometimes, like Joseph Haydn, who arrived in London in 1791, you were deservedly lionised as a genius and basked in royal smiles. At other times, you might hit a dead end, like poor Luigi Boccherini, one of Europe’s foremost exponents of the symphony and the string quartet, whose fate was to spend almost a decade marooned in the Spanish one-horse town to which his employer, a Bourbon prince, had been exiled for marrying a commoner.

By the time thirteen-year-old Wolfgang Amadeus Mozart set out on a trip to Italy in December 1769, he was a seasoned wanderer. His provident father, Leopold, court composer to the archbishop of Salzburg, had already shown off the prodigious boy musician with his sister Nannerl, a gifted pianist, to Empress Maria Theresa in Vienna and Elector Maximilian III of Bavaria in Munich before whisking the family away to France, Holland and England, where ‘little master Mozart’ wowed the cognoscenti with his talents as improviser and contrapuntalist.

In this musical cosmopolis, Italian was the lingua franca for the preparation of scores and the writing of opera libretti. Now Italy itself, over the mountains from Salzburg, lay in readiness for the Mozarts to conquer. Duly furnished with recommendations from Leopold’s inexhaustible contact network, the father and son trundled