It was very exciting when the piece sprang together for the first time

Willem Holsbergen

It will be performed for the first time by the National Symphony Orchestra on 20 September.

"The opportunity to give the world premiere of a Beethoven composition - even a small portion of it - is astonishing," said National Symphony Orchestra music director Leonard Slatkin.

"Aside from the intrinsic interest in anything Beethoven wrote, the story of how this performing version came to exist would probably be viewed as too far-fetched if it were to appear in fiction."

Ludwig van Beethoven began writing the overture with Austrian librettist Joachim von Collin - but abandoned the work when von Collin pulled out, complaining the music was "too gloomy".

Slatkin: Opportunity is "astonishing"

Sketches of the overture were broken up by souvenir hunters after Beethoven's death in 1827, and ended up in Bonn, Berlin and London.

Dutchman Willem Holsbergen decided to let the work see the light of day after hearing of its existence from another fan on a website.

Holsbergen typed notes from the sketches into a special computer programme, which helped him stitch the three parts of the work together.

"It was very exciting when the piece sprang together for the first time, when it came to life," Holsbergen said.

'Great honour'

The work is "pretty dark music most of the time", Holsbergen said, but there are "points of light in it as you would expect from Beethoven".

It had not been difficult to put the pieces together, he said, and described it as "great fun and a great honour" to construct the work.

The overture was intended to accompany the first part of the Macbeth story, where the three witches are talking.

Holsbergen's score will use two flutes, two oboes, two clarinets, two bassoons, four horns, two trumpets, timpani and strings.