Bax's Concertino, started in 1939 and intended for Harriet Cohen, was completed and orchestrated by Graham Parlett in 2007. Here are his programme notes.
Following Bax's death in Cork on 3 October 1953, Harriet Cohen visited The White Horse Hotel in Storrington, Sussex where he had lived for the last thirteen years, and took away his manuscripts, most of which she later bequeathed to the British Library. Among them was the short score of a three-movement work for piano and orchestra with the title 'Concertino', and this is without doubt the abandoned 'small concerto' referred to in Bax's letter to Edwin Evans. The work is in three movements, of which the first two are both complete in the form of a rough score written in pencil, mainly on two staves, while the third is neatly written out in ink as a two-piano score.
In most cases it was fairly easy to determine which notes in the first movement were intended to be played by the solo piano and which were intended for the orchestra since Bax has marked 'Piano' or 'Orch' against certain passages. Sections intended for both piano and orchestra presented more of a problem, and it was sometimes necessary to devise additional passagework for the piano when playing with the orchestra. Bax left only a few indications of the intended orchestration ('str con sord' (muted strings) and 'fag' (bassoons) appear at the opening, for example), but it is clear from the layout of the music that a fairly large orchestra would have been required. The mood is quite dark in places, with echoes of the earlier Winter Legends, and it is much more akin to Bax's later 'northern' works than to the earlier 'Celtic' tone-poems. The slow movement was a little more problematic. Bar 11 has the word 'Orch' written above it, which suggested that the opening was intended for the piano, but there are few other indications of who is meant to play what, though 'clar' (clarinet) and 'horns' are marked against two melodic lines. Another difficulty was the fact that some bars contained nothing but chords, which, left as they were, would have made the movement sound intolerably static; no doubt Bax would have developed these if he had finished the work. It was therefore necessary in several places to elaborate both the orchestral and piano parts. The opening is similar in mood to the slow movement of the later left-hand Concertante, but darker elements intrude, and the music becomes quite grim in places.
The finale was the easiest movement to realise. The solo part on the upper two staves needed hardly any editing, and the orchestral part was also quite explicit, though there is no indication of the intended instrumentation other than the word 'timp', which occurs at one point. The movement is in 3/4 time throughout and is in effect a scherzo containing some of Bax's most consistently jovial and unbuttoned music, quite at odds with the 'perpetual political tension' of which he wrote in his letter to Edwin Evans. It could almost be described as Bax's 'apotheosis of the dance', the phrase that Wagner applied to Beethoven's Seventh Symphony, and indeed the mood, if not the manner, is quite close to the first movement of that work.