The London house Christie’s will present an autograph letter written by the 26-year-old composer to his close friend Baroness von Waldstätten for auction.

It is estimated the letter will fetch from £300,000 to £500,000 ($557,000 to $929,000AUD).

The two-page letter in Mozart’s hand, in German, comprises two pages and was written in the summer of 1782 in Vienna. In it, the composer declares that he will need to get married within two days in order to save his future wife, Constanze, from the scandal of being dragged out of his house by the police.

At the time the letter was written, Constanze was known to be cohabiting under the same roof as Mozart, which prompted her mother, Cäcilia Weber, to send in the police to reclaim her daughter from Mozart’s house to save her reputation. This prompted Mozart to declare the only solution is for him to marry Constanze the next day – or indeed the same day if at all possible.

The couple went on to marry on 4 August 1782.

“Wolfgang Amadeus Mozart is one of the most influential and prolific composers of all time, and we are delighted to unveil such a personal...