I believe this article constitutes the most that is known about J.G. Graeff, at the time of writing.

When Napoleon and his forces attacked the German town of Mainz in 1793, flautist J G Graeff fled his home and escaped by swimming across the river Main with his father’s portrait tucked safely inside his jacket, then he hot-footed it to London where he made a fortune. Such is the wonderful story handed down through generations of Graeff’s descendents as told to me by his gr.gr.etc grand daughter, Sheila Stickley.
It is such an excellent story that it seems a pity to dispel it with the historical fact that by 1793 Graeff was already leading a comfortable life in London as an established member of the musical elite of the city.
He was born in Germany in the town of Mainz, where his father was a prominent government official. J G's parents had intended their son to take up a profession in the church, but due to the young man having such a strong preference for music coupled with an obvious talent, they relented and allowed him to study music instead. As a result, whist still in his early teens [c.1777] Graeff left home, travelling first to Switzerland where he spent five years in Basel, Berne and Lausanne, before going to Paris for a year where he enjoyed considerable success as an instrumentalist.
JG’s skills obviously were much appreciated by one person in Lausanne, and in this poem, printed in the Nouveau Journal de Litérature [1784][1], the poet praises the enchanting quality of Graeff’s flute playing and sorrows that he is departing Lausanne:
A Monsieur Graeff, habile Joueur de Flute
Autrefois Apollon vint dans la Thessalie

Enseigner aux Bergers la sublime harmonie;

Ce Peuple s’adoucit aux doux sons de sa voix

Et des tendres accords il reconnut les Loix.
Ainsi Graeff arriva fur notre heureux rivage 

Et de nouveaux plaisirs nous présenta l’image; 

Oui, de son instrument les tons doux & flatteurs

Charmerent les esprits, & toucherent les cœurs. 

Sous ses habiles doigts sa flute enchanteresse

Nous inspira toujours les plaisirs, la tendresse, 

Et le jeune Berger docile à ses leçons 

Parvint à répéter ses aimables chansons.


Graeff joint à ses talens un heureux caractere,



Il fut en tous les temps intéresser & plaire

Mais il va nous quitter, & malgré les frimats 

Faire parler sa flute en de nouveaux climats 
Puisse-t-il y trouver le bonheur, & la gloire!
Cher Graeff, des Lausannois conserve la mémoire 

Et sois sur tout sensible au tendre sentiment

Qui pour toi dans mon cœur regnera constamment (Lausanne 1784)

To Mr Graeff, accomplished flute player


 Once Apollo went to Thessaly
 
Taught shepherds such sublime harmony;

 They were soothed by the sweet sound of his voice
 
And the gentle chords showed them the truth.
 

Likewise Graeff arrived on our happy shore 

 And introduced us to a new pleasure
 
Yes, the soft, flattering tone of his instrument 

 Charmed the spirit and touched the heart.
 Under his skillful fingers his enchanting flute

 Inspired in us pleasure, tenderness, 

 And the young shepherd obedient to his lessons
 
Managed to repeat those lovely songs.
 

Graeff added a happy character to his talents,
 
He was always interested & pleasing
 
But he is leaving us, despite the frosts
 
To make his flute speak in new climates
 
May he find happiness and glory! 


 Dear Graeff, remember Lausanne
 


And be sensitive to the tender feeling
 That will constantly reign in my heart for you

Graeff received an enviable music education, having been a pupil of both C F Abel and J Haydn. However, the dates of his studies are a matter for conjecture. Contemporary sources including Sainsbury’s Dictionary of Musicians [1827] suggest that they occurred before the young Graeff left his home in Mainz. However, since there is no record of either Abel or Haydn visiting Germany at that time, it is more likely that Graeff’s studies with the masters took place considerably later. Comparison of the where’s and when’s adds up to the possibility that Graeff met Abel in Paris in 1783 and also indicates that his studies with Haydn occurred much later when the great man visited London from 1791. We know that Graeff was in contact with Haydn as there was correspondence[10] between them and they performed in concerts together. In one such concert Graeff performed a Flute Concerto by Mozart and Haydn conducted the first performance of one of his own symphonies. Then in 1797 Graeff dedicated his Three Quartets for a flute violin and violoncello to ‘Dr. Haydn by his late pupil, J.G. Graeff’. [2] The quartets, (published by Linley, price eight shillings) received this favourable review in The Monthly Magazine:
Mr Graeff in these quartettos does honour to his master. The genius of the instruments for which they are written, are well consulted, and their combined effect studied with success. A respectable degree of science as well as considerable freedom of imagination pervade the whole work and recommend it to public notice. We are particularly pleased with the first and third movements of the first quartetto; the subject of the latter of which (a rondeau) is original and striking. The first movement of the second is rich in its style, and the whole of the third is attractive and masterly; especially the first movement which ranks with some of the best instrumental music of the present times. [2]
Graeff had first appeared as a flute soloist in London in 1784 in Salomon’s concerts ‘for the Gentry & Nobility’ at the Assembly Rooms in Hannover Square. Graeff played … with very powerful tone and rapidity of finger … upon a flute not of the new construction ..it had no greater compass than D below.’ [3] Soon he was established as part of the musical scene in London, assisted in large part by his friendship with Munzio Clementi, whom he conceivably may have met before in Switzerland before his days . Clementi was ten years older than Graeff and already a prominent figure in London. Under his guidance, Graeff quickly became sought after as a teacher and performer and switched his main activity to the pianoforte by which he made a fortune. Graeff, professor of Violin/Flute/Piano/Composer[5] was described as a credit to his profession on account of his ‘gentlemanlike conduct and excellent character’[7] and in 1813 he was selected as one of the thirty founding members of the Philharmonic Society[4]. Three years later his name appeared alongside other top musicians of his day [including Attwood, Clementi, Cramer, Beethoven, Cherubini] appended to a letter extolling the virtues of the Metronome newly invented by Maelzel. Published in the Morning Chronicle [6], it states that the device is ‘elegant, portable and reasonable in price … it appears to us to hold out the greatest advantages to young musical practitioners … and serves as a complete guide to the pupil during the absence of the Master’ Advertisements for Graeff’s compositions appeared regularly in the newspapers from 1786 and although they were always overshadowed by Haydn's works, which was very much in vogue at the time, they must have produced a significant income. At that time a loaf of bread in England cost 0/2d. Prices for Graeff’s compositions ranged from 1/6d. for a single song to 7/6d. for a set of flute duets. Using the loaf of bread as a standard of measurement, it would make Graeff’s flute duets cost the equivalent of £60 in today’s money.
Samuel Wesley was another of Graeff’s friends. He was welcomed at Wesley’s house in Highgate as a member of a music party ‘who formed the sweetest harmony consisting principally of Mozart and Haydn’s Musick, which they performed with most exquisite precision and effect’. The two men shared a passion for the music of Bach which was then gaining popularity in London. Graeff possessed a printed edition of Bach’s ‘48’, a rare thing in the 18th century, which he leant to his friend and which Wesley diligently copied out by hand. Wesley dedicated a composition to Graeff a set of variations entitled Jacky Horner [ published by Clementi, 1816]. That they had a familiar and jovial relationship is clear and the following letter was evidently intended to be read ‘tongue in cheek’:
My dear Sir [J G Graeff] You will excuse me asking you upon a sheet of coarse copy paper whether you shall be at leisure this evening and whether I may expect the pleasure of a call from you? As I have nothing to employ me, I think we may amuse ourselves one way or another – I know you have no taste for the sublime or beautiful in music, otherwise I would give you some of Pucitta’s operas, or Von Esch’s Divertimentos with Triangular accompaniments; but as the matter is, I must bear to drudge through some of Bach’s humbug dismal ditties, all so devoid of air, taste, sentiment, science or contrivance, that I am astonished how a sensible man like yourself could ever have held up such an imposter to admiration – it only shows what ignorant pretenders to musical knowledge you Germans are. Not with standing which, I am truly yours. S.Wesley  [11]
In 1802 at the age of forty, Graeff advanced his fortunes further by marrying, Mary Jordan, a wealthy farmer’s daughter from Barnet. A few months later on April 18th,1803 he was officially naturalized and became a Denizen of England. He was sufficiently wealthy to be able to retire early and to make donations to worthy causes, for example five pounds in 1826 to the Fund for Distressed Manufacturers. He lived out the remainder of his life in London and died aged 68 at his home in Southampton Place, Euston Square on February 7th 1829. Sadly he died too soon to see one of his sons, Edward, rewarded by the Society for the Encouragement of the Arts with a large silver medal for his invention of an apparatus that would enable a needlewoman who had lost her hand to continue to do her work. J.G’s wife survived her husband by 5 years. The Sonata in G for flute [opus 5 no.1] by Graeff is a delightful and interesting work with a curious diversity of style. The first movement has a strength of character that reflects the style of late Haydn and is typical of its time [c.1790]. The second movement is soulfully poignant with a quality that seems to look back at CPE Bach, whilst the third movement looks forward in time with a jovial romp that anticipates the style of the Sonata for Strings written by Rossini in 1804. And, if this was not enough, the whole work, despite being firmly rooted in the Classical period, was composed with no other accompaniment than a figured bass - such a mix of styles, such fun realising the piano part for the Trübcher edition. Fun enough that we also created an edition for soprano saxophone.

[1] Nouveau Journal de Litérature. [1784] [2] The Monthly Magazine, or British Register Vol. 3 [3] The symphonies of Joseph Haydn, Volume 1- H C Robbins Landon [4]History of the Philharmonic Society by Birkett Foster [5]Music in London and the Myth of Decline: From Haydn to the Philharmonic By Ian Taylor [6] Morning Chronicle. July 16 1816 [7] The Harmonicum [1829] [8] ‘…Highgate at October 10th 1801’ ‘The letters of Samuel Wesley’by Philip Olleson [9] Memoir of Johann Peter Salomon [ The Harmonicin Vol.8] [10] The Haydn Yearbook: Das Haydn Jahrbuch, Volume 13 [11] [Philip Olleson ‘The letters of Samuel Wesley’] Groves Online British Newpaper Archive Sainsbury’s Dictionary of Musicians [1827] Stickley family history