Charles Filtsch “appears to have received his earliest regular instruction on the piano from Mittag at Vienna.  In 1842 he was in Paris, studying under Chopin and Liszt.  In the summer  of 43 he came to London (at the same time with Ernst, Halle, Sivori, Dreyschock, and Spohr), and appeared twice in public, once on June 14, at St. James’s Theatre, between two of the plays, and again on July 4, at a Matinée of his own at the Hanover Square Rooms.  On the latter occasion, besides the Scherzo in B minor and other pieces of Chopin, he played a Prelude and Fugue of Bach’s and a piece in A from the ‘Temperaments’ of Mendelssohn.  In the last of these he was peculiarly happy.  ‘Presto de Mendelssohn,’ said Spohr, the moment he saw Filtsch seated at the piano at Sir G. Smart’s a few nights after.  He also played at Buckingham Palace before the Queen and Prince Albert.  He was then 13 years old, and his playing is described as most remarkable both for execution and expression — full at once of vigour and feeling, poetry and passion.  (See the Musical Examiner for June 17 and July 8, 1843.)  Every one who met him seems to have loved  him.  He was ‘le petit’ in Paris, and ‘little  Filtsch’ in London.  According to the enthusiastic von Lenz, Chopin said that he played his music better than he himself, while Liszt on one  occasion  exclaimed ‘Quand ce petit voyagera je fermerai boutique.’  (Lenz, ‘Grosse PF. Virtuosen,’ p. 36 ; ‘Beethoven et ses trois Styles,’ i. 229.)  But he was not destined to fulfil the promise of so brilliant a childhood — the  blade was too keen for the scabbard ; and, as Moscheles warned him, he practised too much for his strength ; consumption showed  itself, and he died at Venice on May 11, 1845.”
From A Dictionary of Music and Musicians edited by George Grove, 1879. Filtsch’s entry was written by Grove himself.

“This CHARLES FILTSCH, then, a mere child of scarcely thirteen years’ growth, and for the last two or three years a pupil of the celebrated CHOPIN, has contrived by some powers of magic – for we scarce know how else to account for it – to possess himself of all those perfections of pianoforte playing which are generally sufficiently wondered at in the most matured performers.  Our readers may doubt the truth of all this in its fullest extent, but they have only to hear for themselves and be convinced.  He is a little artless-looking boy, very handsome withal, but very small of stature, who sits him down to the pianoforte, and seems to make sport of the most difficult compositions, in all styles indifferently, playing them by memory, and with a force, brilliance of effect, truth of expression, and accurate perception of their various characteristics, that we verily believe cannot be over-matched.  His selection on this occasion comprised four compositions of CHOPIN, of which the enormous difficulty is much more perceptible than their beauty; a charming little “serenade” by MOSCHELLES; the magnificent movement in F major from MENDELSSOHN’S Temperaments ; and a prelude and fugue in C sharp major from SEBASTIAN BACH’S “forty-eight;” and in all these pieces, different and even opposite in style though they be, we can conscientiously affirm that this little prodigy not only exceeded everything that could have been expected of a child, but equally everything that could be required of the most practised man.  His most extraordinary performances were, without doubt, the movement from the Temperaments, and the prelude and fugue of BACH; and those who know the pieces referred to will readily conceive what that playing must have been which not barely satisfied but enraptured the most accurate critics of performance and the most ardent admirers of the music performed.  We put the matter of precocity at once out of the question, and do not hesitate to express our opinion that CHARLES FILTSCH is a veritable wonder among pianists.

A selection of vocal music, excellently sung by Misses MARSHALL, DOLBY, and BASSANO, and Signor GIUBILEI, completed the programme of the concert, which was extremely well attended.”

The Atlas, 8 July 1843