Christopher Morley on the delayed premiere of a work by Arnold Bax.

Though not in fact quite as common as popular conception would have us believe, the idea of composers being inspired by their special muse has some roots in reality.

Off the top of my head, Beethoven, Verdi, Puccini and Debussy come to mind as having their muse-ical moments. Berlioz, Schumann, Chopin, Wagner, Mahler, Elgar and Britten (let’s not underestimate his devotion to Peter Pears) were more permanently smitten. And Arnold Bax had a passionate relationship with the pianist Harriet Cohen.

Bax, who was Master of the Queen’s Music when he died on October 3, 1953, had a brooding, arch-romantic Celtic temperament, and in Cohen he found a soulmate to provide fuel to fire his poetic soul.

But though they were mutually obsessed with each other, both parties were not above conducting liaisons with other lovers. And indeed Bax did not tell Harriet of his wife’s death until many months after her demise, as he was currently frying other fish. Harriet was devastated, as she had always counted on marrying the composer once he was free.

Yet this devastatingly beautiful woman had herself dabbled at length with other suitors, as is chronicled in Music & Men: the life and loves of Harriet Cohen by Helen Fry, recently published by the History Press (£20).

This is a handsomely produced book, with many fascinating photographs (one of Harriet in a diaphanous gown, provocatively posed, bears a comment from her great friend George Bernard Shaw: “What a photograph! Men have been divorced for less!”).

But I wouldn’t rely on it as a source of reliable musical information. My suspicions were aroused very early on when Helen Fry refers to Bax’s “famous tone-poem Tintagel Castle,” a work which Barbirolli, Boult, Tod Handley and the rest of us always thought was called, simply, Tintagel. Worse comes on the next page, when Fry tells us “the Spanish composer Manuel de Falla was so taken by Harriet Cohen that he dedicated his famous work Nights in the Gardens of Spain to her”.

He didn’t: my score tells me Ricardo Vines, a pianist who was an important interpreter of many European composers in the early years of the 20th Century, was the dedicatee.

Among the many works the besotted Bax composed for Harriet Cohen was a three-movement Concertino for Piano and Orchestra, begun in 1939 but never completed, for reasons we can only surmise. Disenchantment? Disillusionment? Dissatisfaction with the piece? The onset of the Second World War? We shall probably never know, but the work has had to wait 70 years for its first public performance, which takes place at Stratford-upon-Avon Civic Hall tonight, with Mark Bebbinbgton as soloist and David Curtis conducting the Orchestra of the Swan.

On Bax’s death Harriet seized all his manuscripts and eventually bequeathed them to the British Library, where the sketches for the Concertino, remarkably substantial, were discovered by Graham Parlett, as he explains: “I first came across the Concertino back in the 1970s, when I was working my way through the scores that Harriet Cohen had bequeathed to the British Library. But it wasn’t until the mid-1990s that I began to look at it seriously. The first two movements exist in Bax’s manuscript complete – in the sense there are no bars missing – as a rough piano score on two staves, with several indications of which notes were intended for the soloist, and which for the orchestra.

“Sometimes it was necessary to devise some passagework for the piano when it was obviously meant to be playing with the orchestra. The second movement needed a little more elaboration in places: there were passages consisting merely of a succession of chords, which would have sounded too static if left unadorned, but my policy was to add as little as possible. The third movement was the easiest to arrange, as it existed complete in the form of a two-piano score. The solo part needed hardly any editing, while the orchestral part, on two staves, was virtually complete as it stood. I had to add a little harmony in a few places, but not much else was needed other than to arrange it for orchestra.

“I transcribed it by hand and even made a rough orchestral draft of the third movement purely for my own amusement. Nothing further was done until December 2005, when I decided to put the whole of Bax’s short (piano) score on to my computer.

“Finally, in 2007, I made a draft full score of the complete work. Lewis Foreman, probably the world’s greatest Bax expert, heard about it, and mentioned it to Bruce Phillips of the John Ireland Trust, who was casting around to find a coupling for Mark Bebbington’s proposed recording of Ireland’s Piano Concerto for the SOMM label.

“He asked me to send copies to Mark and to David Curtis, the conductor of the Orchestra of the Swan. They both expressed interest in it, and in May this year it was duly recorded in Birmingham Town Hall, along with the Ireland Concerto and Ireland’s Legend.”

* The CD will be released in October, but the public premiere will be given tonight, as part of “The Last Night of the Stratford Summer Proms” at the Civic Hall, Stratford-upon-Avon, at 8pm (Box office: 01789 207100).