'The performance of Mozart's [D minor] Concerto by M. Mendelssohn [directing from the keyboard] was perfect. The scrupulous exactness with which he gave the author's text, without a single addition or new reading of his own, the precision in his time, together with the extraordinary accuracy of his execution, excited the admiration of all present; and this was increased, almost to rapture, by his two extemporaneous cadences [none by Mozart surviving], in which he adverted with great address to the subjects of the concerto, and wrought up his audience almost to the same pitch of enthusiasm which he himself had arrived at. The whole of this concerto he played from memory.'

- The Harmonicon, London June 1833, reviewing a Philharmonic Society concert, Hanover Square Rooms, May 13th 1833

'The pianoforte playing was ... the chief treat. It is rarely that I have been so delighted, without novelty or suprise having some share in the delight. It would have been absurd to expect much pianism, as distinct from music, in the performance of one writing so straightforwardly, and without the coquetries of embroidery, as Mendelssohn ... his performance had none of the exquisite finesses of Moscheles, on the score of which it has been elsewhere said that "there is wit in his playing;" none of the delicate and plaintive and spiritual seductions of Chopin, who swept the keys with so insinuating and gossamer a touch, that the crudest and most chromatic harmonies of his music floated away under his hand, indistinct, yet not unpleasing, like the wild and softened discords of the Æolian harp; none of the brilliant extravagances of Liszt, by which he illuminates every composition he undertakes with a living but lightening fire, and imparts to it a soul of passion, or a dazzling vivacity, the interpretation never contradicting the author's intention, but more poignant, more intense, more glowing, than ever the author dreamed of. And yet no one that ever heard Mendelssohn's pianoforte playing could find it dry, could fail to be excited and fascinated by it, despite of its want of all the caprices and colourings of his contemporaries. Solidity, in which the organ-touch is given to the piano without the organ ponderosity; spirit ... animating, but never intoxicating, the ear; expression, which, making every tone sink deep, required not the garnishing of trills and appoggiature, or the aid of changes of time - were among its outward and salient characteristics.'

- Henry Fothergill Chorley, Modern German Music (London 1854)

'At the last concert of the season [Philharmonic Society, Hanover Square Rooms, June 24th 1844] ... he played, for the first time in England, Beethoven's Pianoforte Concerto in G major [directing from the keyboard].

'At the rehearsal, on Saturday the 22nd, [the composer's own being unavailable] he enriched the first movement with a magnificent extempore cadenza, in which he worked up the varied subjects of the piece with the skill which never failed him when he gave the reins to his exuberant fancy. On reaching the shake at its close he found the orchestra a little uncertain in taking up its point. In order to remove all fear of misunderstanding, he again extemporised a cadenza entirely different from the first, though not a whit less beautiful. The orchestra again missed its point so decidedly that he found it necessary to make a third trial. This last cadenza was by far the longest and most interesting of the three, and totally different, both in manner and in style, from its predecessors. It had, moreover, the effect of rendering the orchestral point so safe that no fear whatever was anticipated with regard to the Monday performance.

'It will be readily understood that all present looked forward to this performance with intensest excitement; feeling certain that another new cadenza would be improvised at the concert. And it really was so. The same subjects were placed in so different a light, that their treatment bore not the slightest shade of resemblance to the Saturday performance, until the approach of the final shake, which was so arranged as to enable the orchestra to take up its point with the most perfect accuracy.'

- W.S. Rockstro, Felix Mendelssohn Bartholdy (London 1884)

Rockstro's memory failed him possibly twice. The concert in question was the penultimate programme of the 1844 season, not the last. And, should we choose to so interpret, it wasn't Mendelssohn who gave the first performance in England of the G major Concerto but Cipriani Potter (Philharmonic Society, Argyll Rooms, March 7th 1825). Beethoven's cadenzas were only published in 1864. Till much later it was customary for players - Brahms and Clara Schumann not least among the many - to elaborate their own. AO