It is easily forgotten that silent movies were never silent. In classier cinemas one usually found an orchestra of indeterminate size scrabbling furiously in pursuit of the villain, or sympathetically setting the mood for a love scene. Even in smaller establishments there would be at least a pianist banging away.

For the most significant films, a full score would be commissioned, and a few of these rarities were so good that they have survived to the present day. Gottfried Huppertz’s score for Metropolis, written in 1927 to accompany the dazzling film by Fritz Lang, is one such example. The useful notes that accompany the CD give us a story of the scrupulous way in which Huppertz approached his job, including visits to the set during filming. Only with the discovery of the missing 20 minutes of footage in 2008 has the fully restored film and its score been rehabilitated. 

Interest in the film was rekindled in 1983 when Giorgio Moroder released a partial restoration with a rock score he himself had composed with a little help from his friends, including Freddie Mercury of Queen. Whatever the merits and curiosities of that version, the original 1927 score...