[3] In the same letter he stated that both he and his brother 'could supplement orchestral skills with duets, concertos, wind octets and basset horn trios', the latter together with Raymund Griesbacher.

In October 1781 he wrote of the first performance of the sextet version of his E-flat Serenade K 375: "The six gentlemen who executed it are poor beggars who, however, play quite well together, particularly the first clarinet and the two horns."

[6] Stadler's evident preoccupation with the chalumeau register(the lowest range a clarinet can be played at) is significant in view of Mozart's subsequent exploitation of its idiomatic potential.

[7] Schink here clearly refers to a performance of Mozart's Serenade for thirteen instruments K 361/370a, which probably formed part of Stadler's benefit concert at the National Court Theatre advertised in the Wienerblättchen of 22 March 1784: "Herr Stadler senior, in present service of His Majesty the Emperor, will hold a musical concert for his own benefit, at which will be given, among other well chosen pieces, a great wind piece of a very special kind composed by Herr Mozart.

The arrival in Vienna of the Bohemian players Anton David and Vincent Springer proved an important catalyst for Mozart's basset horn writing.

[9] Mozart's espousal of the basset horn really began in earnest in late 1783 when he produced over a period of two years thirteen works for that instrument: The latter dates from the end of 1785.

This remarkable activity was undoubtedly brought about by the availability of four excellent clarinet and basset horn players – the Stadlers, David and Springer – who in combination must have inspired the scoring of Mozart's Serenade K 361/370a, in addition to more ritualistic works such as the Adagio K 411/484a.

Indeed, the basset horn came to be associated with Masonic ritual, for which its special character was ideally suited, and Anton Stadler was admitted to the 'Zum Palmbaum' ('Palm Tree') lodge on 27 September 1785.

On 20 October of that year he and Mozart performed at a benefit concert (to pay for David's and Springer's journey home) organised by the Palm Tree and Three Eagles lodges of the Viennese Masonic order, and on 17 November Mozart's most important piece of Masonic music, the Maurerische Trauermusik K 477/479a, was performed during a Lodge of Sorrows for the deaths of two Brothers, Georg August, Duke of Mecklenburg-Strelitz, and Franz, Count Esterhazy of Galántha.

Mozart's Clarinet Trio K 498 was written for the pianist Francesca von Jacquin and must have been first played at the family house, with the participation of Stadler and the composer himself.

Although the eloquence of Mozart's clarinet writing for Stadler testifies to a remarkable musical relationship, surviving evidence of their personal friendship remains fragmentary.

In any case, Mozart's nickname for the clarinettist reveals a shared sense of humour; 'Notschibinitschibi' is a combination of two words – 'Notschibi' meaning a poor booby or miser and 'Nitschibi' a young man of follies.

A surviving programme for a concert on 20 February 1788 documents an important milestone in the history of Stadler and Mozart, heralding the arrival of a newly extended clarinet.

[14] By 1796 Stadler had returned to Vienna, taking up his post alongside his brother, and starting composing works for basset horn and clarinet, a number of which were published.

The document, based on a set of questions provided by the count, recommends a rigorous education, combining performance, music theory and composition with schooling in a broad range of subjects.

He also has wise words on how to behave in the profession, suggesting instrumentalists 'not to drown out singers, not hold back or press forward in tempo, not publicly censure another's chance mistake, nor ridicule their colleagues'.